Endangered and Threatened Wildlife and Plants; Endangered Species Status for Chamaecrista lineata var. keyensis (Big Pine Partridge Pea), Chamaesyce deltoidea ssp. serpyllum (Wedge Spurge), and Linum arenicola (Sand Flax), and Threatened Species Status for Argythamnia blodgettii (Blodgett's Silverbush), 58535-58567 [2015-24291]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 80, Number 188 (Tuesday, September 29, 2015)]
[Proposed Rules]
[Pages 58535-58567]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-24291]



[[Page 58535]]

Vol. 80

Tuesday,

No. 188

September 29, 2015

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for Chamaecrista Lineata Var. Keyensis (Big Pine Partridge Pea), 
Chamaesyce Deltoidea Ssp. Serpyllum (Wedge Spurge), and Linum Arenicola 
(Sand Flax), and Threatened Species Status for Argythamnia Blodgettii 
(Blodgett's Silverbush); Proposed Rule

Federal Register / Vol. 80 , No. 188 / Tuesday, September 29, 2015 / 
Proposed Rules

[[Page 58536]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2015-0137]; [4500030113]
RIN 1018-AZ95


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for Chamaecrista lineata var. keyensis (Big Pine Partridge Pea), 
Chamaesyce deltoidea ssp. serpyllum (Wedge Spurge), and Linum arenicola 
(Sand Flax), and Threatened Species Status for Argythamnia blodgettii 
(Blodgett's Silverbush)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service or USFWS), 
propose to list four plants from south Florida under the Endangered 
Species Act of 1973, as amended (Act): Chamaecrista lineata var. 
keyensis (Big Pine partridge pea), Chamaesyce deltoidea ssp. serpyllum 
(wedge spurge), and Linum arenicola (sand flax) as endangered species, 
and Argythamnia blodgettii (Blodgett's silverbush) as a threatened 
species. If we finalize this rule as proposed, it would extend the 
Act's protections to these plants.

DATES: We will accept comments received or postmarked on or before 
November 30, 2015. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for 
public hearings, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by November 13, 2015.

ADDRESSES: You may submit comments by one of the following methods:
    (1) Electronically: Go to the Federal eRulemaking Portal: https://www.regulations.gov. In the Search box, enter FWS-R4-ES-2015-0137, 
which is the docket number for this rulemaking. Then, in the Search 
panel on the left side of the screen, under the Document Type heading, 
click on the Proposed Rules link to locate this document. You may 
submit a comment by clicking on ``Comment Now!''
    (2) By hard copy: Submit by U.S. mail or hand-delivery to: Public 
Comments Processing, Attn: FWS-R4-ES-2015-0137; U.S. Fish and Wildlife 
Service, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
    We request that you send comments only by the methods described 
above. We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see Public Comments, below, for more information).

FOR FURTHER INFORMATION CONTACT: Larry Williams, State Supervisor, U.S. 
Fish and Wildlife Service, South Florida Ecological Services Field 
Office, 1339 20th Street, Vero Beach, FL 32960; by telephone 772-562-
3909; or by facsimile 772-562-4288. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish a rule. Under the Act, if we determine that 
a species is an endangered or threatened species throughout all or a 
significant portion of its range, we must publish a proposed rule to 
list the species in the Federal Register and make a determination on 
our proposal within 1 year. Listing a species as an endangered or 
threatened species can only be completed by issuing a rule.
    This rule proposes the listing of Chamaecrista lineata var. 
keyensis, Chamaesyce deltoidea ssp. serpyllum, and Linum arenicola as 
endangered species, and Argythamnia blodgettii as a threatened species. 
The four plants are candidate species for which we have on file 
sufficient information on biological vulnerability and threats to 
support preparation of a listing proposal, but for which development of 
a listing rule has until now been precluded by other higher priority 
listing activities. This rule reassesses all available information 
regarding status of and threats to the four plants.
    The basis for our action. Under the Act, we may determine that a 
species is an endangered or threatened species based on any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. We have determined that the threats to 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii consist 
primarily of habitat loss and modification through urban and 
agricultural development, and lack of adequate fire management (Factor 
A); and the proliferation of nonnative invasive plants, stochastic 
events (hurricanes and storm surge), maintenance practices used on 
roadsides and disturbed sites, and sea level rise (Factor E). Existing 
regulatory mechanisms have not been adequate to reduce or remove these 
threats (Factor D).
    We will seek peer review. We will seek comments from independent 
specialists to ensure that our determinations are based on 
scientifically sound data, assumptions, and analyses. We will invite 
these peer reviewers to comment on this listing proposal.

Information Requested

Public Comments

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned governmental agencies, 
Native American tribes, the scientific community, industry, or any 
other interested parties concerning this proposed rule. We particularly 
seek comments concerning:
    (1) The four plants' biology, range, and population trends, 
including:
    (a) Biological or ecological requirements of these plants, 
including habitat requirements for establishment, growth, and 
reproduction;
    (b) Genetics and taxonomy;
    (c) Historical and current ranges, including distribution patterns;
    (d) Historical and current population levels, and current and 
projected trends; and
    (e) Past and ongoing conservation measures for the plants, their 
habitats, or both.
    (2) Factors that may affect the continued existence of these 
plants, which may include habitat modification or destruction, 
overutilization, disease, predation, the inadequacy of existing 
regulatory mechanisms, or other natural or manmade factors.
    (3) Biological, commercial trade, or other relevant data concerning 
any threats (or lack thereof) to these plants and existing regulations 
that may be addressing those threats.
    (4) Current or planned activities in the areas occupied by these 
plants and possible impacts of these activities on these plants.
    (5) Additional information concerning the biological or ecological 
requirements

[[Page 58537]]

of these plants, including pollination and pollinators.
    (6) Scientific information or analysis informing whether these 
plants more closely meet the definition of endangered or of threatened 
under the Act.
    Please include sufficient information with your submission (such as 
scientific journal articles or other publications) to allow us to 
verify any scientific or commercial information you include.
    Please note that submissions merely stating support for or 
opposition to the action under consideration without providing 
supporting information, although noted, will not be considered in 
making a determination, as section 4(b)(1)(A) of the Act (16 U.S.C. 
1531 et seq.) directs that determinations as to whether any species is 
an endangered or threatened species must be made ``solely on the basis 
of the best scientific and commercial data available.''
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We request 
that you send comments only by the methods described in the ADDRESSES 
section.
    If you submit information via https://www.regulations.gov, your 
entire submission--including any personal identifying information--will 
be posted on the Web site. If your submission is made via a hardcopy 
that includes personal identifying information, you may request at the 
top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so. We 
will post all hardcopy submissions on https://www.regulations.gov.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, South Florida Ecological Services Field Office (see 
FOR FURTHER INFORMATION CONTACT).

Public Hearing

    Section 4(b)(5) of the Act provides for one or more public hearings 
on this proposal, if requested. Requests must be received within 45 
days after the date of publication of this proposed rule in the Federal 
Register. Such requests must be sent to the address shown in the FOR 
FURTHER INFORMATION CONTACT section. We will schedule public hearings 
on this proposal, if any are requested, and announce the dates, times, 
and places of those hearings, as well as how to obtain reasonable 
accommodations, in the Federal Register and local newspapers at least 
15 days before the hearing.

Peer Review

    In accordance with our joint policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), we will seek the expert 
opinions of at least three appropriate and independent specialists 
regarding this proposed rule. The purpose of peer review is to ensure 
that our listing determinations are based on scientifically sound data, 
assumptions, and analyses. The peer reviewers have expertise in the 
biology, habitat, and conservation status of these plants, which will 
inform our determinations. We invite comment from the peer reviewers 
during the public comment period.

Previous Federal Actions

    On January 9, 1975, as directed by the Act, the Secretary for the 
Smithsonian Institution submitted a report to Congress on potential 
endangered and threatened plant species of the United States 
(Smithsonian 1975, entire). The report identified more than 3,000 plant 
species as potentially either endangered or threatened, including 
Argythamnia blodgettii, Chamaecrista lineata var. keyensis (under the 
former name Cassia keyensis), Chamaesyce deltoidea ssp. serpyllum 
(under the name Chamaesyce (Euphorbia) deltoidea ssp. serpyllum), and 
Linum arenicola (Smithsonian 1975, pp. 56, 58, 61, 81). On July 1, 
1975, we published in the Federal Register (40 FR 27824) our 
notification that we considered this report to be a petition to list 
the identified plants as either endangered or threatened under the Act. 
The 1975 notice solicited information from Federal and State agencies, 
and the public, on the status of the species.
    On December 15, 1980, we published in the Federal Register (45 FR 
82480) our notice of review of plant taxa for listing as endangered or 
threatened species. In that document, Argythamnia blodgettii, 
Chamaecrista lineata var. keyensis (under the former name Cassia 
keyensis), Chamaesyce deltoidea ssp. serpyllum (under the former name 
Euphorbia deltoidea ssp. serpyllum), and Linum arenicola were 
identified as Category 1 species (taxa for which we had enough 
biological information to support listing as either endangered or 
threatened). As a result, we considered all four plants to be 
candidates for addition to the Federal List of Endangered and 
Threatened Plants. The 1980 notice solicited information from Federal 
and State agencies, and the public, on the status of the four plant 
species.
    On November 28, 1983, we published a document in the Federal 
Register (48 FR 53640) assigning a listing priority number (LPN) to two 
of the four plant species in accordance with our Listing Priority 
Guidance (48 FR 43098; September 21, 1983). Argythamnia blodgettii and 
Linum arenicola were assigned an LPN of 2, which meant that information 
that the Service possessed indicated that proposing to list as 
endangered or threatened was possibly appropriate but we lacked 
substantial information on biological vulnerability and threat(s) to 
support a proposed listing.
    On September 27, 1985, we published a document in the Federal 
Register (50 FR 39526) assigning LPNs to all four of the plant species 
in accordance with our Listing Priority Guidance (48 FR 43098; 
September 21, 1983). Argythamnia blodgettii and Linum arenicola both 
retained an LPN of 2, which meant that information that the Service 
possessed indicated that proposing to list as endangered or threatened 
was possibly appropriate but we lacked substantial information on 
biological vulnerability and threat(s) to support a proposed listing. 
Chamaecrista lineata var. keyensis (under the former name Cassia 
keyensis) and Chamaesyce deltoidea ssp. serpyllum (under the former 
name Euphorbia deltoidea ssp. serpyllum) were both assigned an LPN of 
1, which meant the Service had on file substantial information on 
biological vulnerability and threat(s) to support the appropriateness 
of proposing to list as endangered or threatened. We recognized at that 
time that any proposed listing action may take ``some years'' because 
of the ``large number of taxa'' at issue.
    The 1990 candidate notice of review (CNOR) published in the Federal 
Register on February 21, 1990 (55 FR 6184). In that CNOR, Argythamnia 
blodgettii and Linum arenicola both retained an LPN of 2, and 
Chamaecrista lineata var. keyensis and Chamaesyce deltoidea ssp. 
serpyllum both retained an LPN of 1. Candidate species are assigned 
LPNs based on immediacy and magnitude of threats, as well as taxonomic 
status. The lower the LPN, the higher priority that species is for us 
to determine appropriate action using our available resources. We 
determined at that time that proposing to list was warranted, but was 
precluded due to workloads and priorities.
    All four plants remained on the candidate list in the 1993 CNOR (58 
FR 51144; September 30, 1993), with Argythamnia blodgettii and Linum 
arenicola both retaining an LPN of 2, and Chamaecrista lineata var. 
keyensis

[[Page 58538]]

and Chamaesyce deltoidea ssp. serpyllum being assigned an LPN of 3C 
(taxa that have proven to be more abundant or widespread than 
previously believed and/or those that are not subject to any 
identifiable threat).
    The 1999 CNOR (64 FR 57534; October 25, 1999) retained Chamaecrista 
lineata var. keyensis and Chamaesyce deltoidea ssp. serpyllum as 
candidates and assigned an LPN of 6 to both, retained Linum arenicola 
as a candidate and assigned an LPN of 2, and retained Argythamnia 
blodgettii as a candidate and assigned an LPN of 11.
    Chamaecrista lineata var. keyensis and Chamaesyce deltoidea ssp. 
serpyllum remained on the candidate list from 2001 to 2006, with the 
LPN of 6 (66 FR 54808, October 30, 2001; 67 FR 40657, June 13, 2002; 69 
FR 24876, May 4, 2004; 70 FR 24870, May 11, 2005; 71 FR 53756, 
September 12, 2006). In the December 6, 2007, CNOR (72 FR 69034), we 
changed the LPN of Chamaecrista lineata var. keyensis and Chamaesyce 
deltoidea ssp. serpyllum from a 6 to a 9 because the threats to the 
species were found to be of lower magnitude than previously known. 
Chamaecrista lineata var. keyensis and Chamaesyce deltoidea ssp. 
serpyllum remained on the candidate list as published in the CNORs from 
2008 to 2014 with the LPN of 9 (73 FR 75176, December 10, 2008; 74 FR 
57804, November 9, 2009; 75 FR 69222, November 10, 2010; 76 FR 66370, 
October 26, 2011; 77 FR 69994, November 21, 2012; 78 FR 70104, November 
22, 2013; 79 FR 72450, December 5, 2014).
    Linum arenicola remained on the candidate list from 2001 to 2009, 
with the LPN of 2 (66 FR 54808, October 30, 2001; 67 FR 40657, June 13, 
2002; 69 FR 24876, May 4, 2004; 70 FR 24870, May 11, 2005; 71 FR 53756, 
September 12, 2006; 72 FR 69034, December 6, 2007; 73 FR 75176, 
December 10, 2008; 74 FR 57804, November 9, 2009). In the November 10, 
2010, CNOR (75 FR 69222), we changed the LPN of L. arenicola from a 2 
to a 5 because of the threats to the species were found to be of lower 
magnitude than previously known and new data showing a larger 
population. L. arenicola remained on the candidate list as published in 
the CNORs from 2011 to 2014 with the LPN of 5 (76 FR 66370, October 26, 
2011; 77 FR 69994, November 21, 2012; 78 FR 70104, November 22, 2013; 
79 FR 72450, December 5, 2014).
    Argythamnia blodgettii remained on the candidate list from 2001 to 
2014, with the LPN of 11 (66 FR 54808, October 30, 2001; 67 FR 40657, 
June 13, 2002; 69 FR 24876, May 4, 2004; 70 FR 24870, May 11, 2005; 71 
FR 53756; September 12, 2006; 72 FR 69034, December 6, 2007; 73 FR 
75176, December 10, 2008; 74 FR 57804, November 9, 2009; 75 FR 69222, 
November 10, 2010; 76 FR 66370, October 26, 2011; 77 FR 69994, November 
21, 2012; 78 FR 70104, November 22, 2013; 79 FR 72450, December 5, 
2014).
    For all four of the plant species, the 2005 CNOR (70 FR 24870; May 
11, 2005) included a ``warranted but precluded'' finding in response to 
a May 11, 2004, petition to list the species.
    On May 10, 2011, as part of a settlement agreement with a 
plaintiff, the Service filed a proposed work plan with the U.S. 
District Court for the District of Columbia. The work plan would enable 
the agency to, over a period of 6 years, systematically review and 
address the needs of more than 250 species listed within the 2010 CNOR, 
including Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii, to determine if 
these species should be added to the Federal Lists of Endangered and 
Threatened Wildlife and Plants. This work plan would enable the Service 
to again prioritize its workload based on the needs of candidate 
species, while also providing State wildlife agencies, stakeholders, 
and other partners clarity and certainty about when listing 
determinations will be made. On July 12, 2011, the Service reached an 
agreement with another plaintiff group and further strengthened the 
work plan, which would allow the agency to focus its resources on the 
species most in need of protection under the Act. These agreements were 
approved by the court on September 9, 2011. The four species are 
proposed for listing pursuant to these agreements.

Background

    It is our intent to discuss below only those topics directly 
relevant to the listing of Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, and Linum arenicola as endangered, 
and Argythamnia blodgettii as threatened, in this proposed rule.
Chamaecrista lineata var. keyensis (Big Pine partridge pea)
Species Description
    Chamaecrista lineata var. keyensis is a small, prostrate to 
ascending, perennial, herbaceous shrub that is 10-80 centimeters (cm) 
(3.9-31.5 inches (in)) tall, with yellow flowers and pinnately compound 
leaves (each leaf consists of a main stem with multiple leaflets lined 
up along on each side). It has one to several branched stems arising 
from a contorted rootstock. New branches are covered in soft, fuzzy 
hairs. The leaves are 1.7-4.0 cm (0.7-1.6 in) long, with 5 to 9 pairs 
of leaflets. Flowers consist of five sepals 9-20 mm (0.4-0.8 in) long 
that are fused together near their bases; five yellow petals 11-15 mm 
(0.4-0.6 in) long, with one slightly larger than the others; 10 
reddish-purple stamens; and a single, elongate style. The fruit is an 
elongate pod, roughly similar to that of a pea, 33-45 mm (1.3-1.8 in) 
long and 4.5-5.0 mm (0.19-0.17 in) wide, with a soft fuzzy texture, 
which turns gray with age and eventually split open to release seeds 
(Irwin and Barneby 1982, p. 757; Small 1933, pp. 662-663).
Taxonomy
    John Loomis Blodgett was the first to collect Chamaecrista lineata 
var. keyensis, sometime between 1838 and 1852, on Big Pine Key (Bradley 
and Gann 1999, p. 17). Pollard (1894, p. 217) assigned the plants on 
Big Pine Key to the existing taxon Cassia grammica. John K. Small 
(1903, p. 587; 1913, p. 58) followed this usage, but used the genus 
Chamaecrista (considered a subgenus within Cassia or a genus unto 
itself variously by many authors). In 1917, Pennell (p. 344) recognized 
the Big Pine Key plant as a distinct endemic species, naming it 
Chamaecrista keyensis. This name was retained by Small (1933, p. 663) 
in his Manual of the Southeastern Flora. In an exhaustive study of 
Cassia and Chamaecrista, Irwin and Barneby (1982, p. 757) assigned 
plants in Florida and parts of the West Indies to the existing taxon 
Chamaecrista lineata, and assigned the Big Pine Key plants to var. 
keyensis, retaining them as endemic to the Florida Keys. Isely (1990, 
p. 33), Wunderlin (1998, p. 348), and Wunderlin and Hansen (2003, p. 
441) have followed this treatment. The online Atlas of Florida Vascular 
Plants (Wunderlin and Hansen 2014, p. 1) uses Chamaecrista lineata var. 
keyensis. The Integrated Taxonomic Information System (2015, p. 1) uses 
the name Chamaecrista lineata var. keyensis and indicates that this 
taxonomy is accepted. Based upon the best available scientific 
information, Chamaecrista lineata var. keyensis is a distinct taxon, 
endemic to the lower Keys in Monroe County, Florida. Synonyms are 
Cassia keyensis (Pennell) J.F. Macbr and Chamaecrista keyensis Pennell. 
Chamaecrista lineata var. keyensis is related to, and superficially 
resembles, Chamaecrista fasciculata, the partridge pea, a common 
species which occurs throughout Florida.

[[Page 58539]]

Climate
    The climate of south Florida where Chamaecrista lineata var. 
keyensis occurs is classified as tropical savanna and is characterized 
by distinct wet and dry seasons and a monthly mean temperature above 18 
degrees Celsius ([deg]C) (64.4 degrees Fahrenheit ([deg]F)) in every 
month of the year (Gabler et al. 1994, p. 211). Freezes can occur in 
the winter months, but are rare at this latitude in south Florida. 
Rainfall in the lower Keys, where C. lineata var. keyensis occurs 
exclusively, varies from an annual average of 89-102 cm (35-40 in). 
Approximately 75 percent of yearly rainfall occurs during the wet 
season from June through September (Snyder et al. 1990, p. 238).
Habitat
    Chamaecrista lineata var. keyensis occurs in pine rocklands of the 
lower Florida Keys, and adjacent disturbed sites, including roadsides.
    Pine Rocklands: Pine rocklands are a unique and highly imperiled 
ecosystem found on limestone substrates in south Florida and a few 
islands in the Bahamas. In Florida, pine rocklands are located on the 
Miami Rock Ridge in present day Miami and in Everglades National Park, 
in the Florida Keys, and in the Big Cypress Swamp. While all four 
plants in this proposed rule occur primarily in pine rocklands, they 
have not been recorded in the Big Cypress Swamp area. Pine rocklands 
differ to some degree between and within these areas with regard to 
substrate (e.g., amount of exposed limestone, type of soil), elevation, 
hydrology, and species composition (both plant and animal).
    Pine rocklands occur in a mosaic with primarily two other natural 
community types--rockland hammock and marl prairie. Pine rocklands 
grade into rockland hammock; pine rocklands have an open pine canopy, 
and rockland hammock has a closed, hardwood canopy. Marl prairies 
differ from pine rocklands in having no pines, an understory dominated 
by grasses and sedges, and a minimal cover of shrubs (FNAI 2010, p. 
63).
    The total remaining acreage of pine rocklands in Miami-Dade and 
Monroe Counties is now 8,981 hectares (ha) (22,079 acres (ac)) 
(approximately 8,140 ha (20,100 ac)) in Miami-Dade County, and 801 ha 
(1,979 ac) in the Florida Keys (Monroe County).
    Pine rocklands are characterized by an open canopy of Pinus 
elliottii var. densa (South Florida slash pine) with a patchy 
understory of tropical and temperate shrubs and palms and a rich 
herbaceous layer of mostly perennial species, including numerous 
species endemic to South Florida. Outcrops of weathered oolitic (small, 
rounded particles or grains) limestone are common, and solution holes 
may be present. This subtropical, pyrogenic flatland can be mesic or 
xeric depending on landscape position and associated natural 
communities (FNAI 2010a, p. 1).
    Pine rocklands occur on relatively flat, moderately to well-drained 
terrain from 2-7 meters (m) (6.5 to 23 feet (ft)) above sea level (FNAI 
2010a, p. 2). The oolitic limestone is at or very near the surface, and 
there is very little soil development. Soils are generally composed of 
small accumulations of nutrient-poor sand, marl, clayey loam, and 
organic debris in depressions and crevices in the rock surface. Organic 
acids occasionally dissolve the surface limestone causing collapsed 
depressions in the surface rock called solution holes (FNAI 2010a, p. 
1). Drainage varies according to the porosity of the limestone 
substrate, but is generally rapid. Consequently, most sites are wet for 
only short periods following heavy rains. During the rainy season, 
however, some sites may be shallowly inundated by slow-flowing surface 
water for up to 60 days each year (FNAI 2010a, p. 1).
    Pine rocklands have an open canopy of South Florida slash pine, 
generally with multiple age classes. The diverse, open shrub and 
subcanopy layer is composed of more than 100 species of palms and 
hardwoods (FNAI 2010a, p. 1), most derived from the tropical flora of 
the West Indies (FNAI 2010a, p. 1). Many of these species vary in 
height depending on fire frequency, getting taller with time since 
fire. These may include Serenoa repens (saw palmetto), Sabal palmetto 
(cabbage palm), Coccothrinax argentata (silver palm), Thrinax morrisii 
(Key thatch palm), Myrica cerifera (wax myrtle), Rapanea punctata 
(myrsine), Metopium toxiferum (poisonwood), Byrsonima lucida 
(locustberry), Dodonaea viscosa (varnishleaf), Tetrazygia bicolor 
(tetrazygia), Guettarda scabra (rough velvetseed), Ardisia 
escallonioides (marlberry), Psidium longipes (longstalked stopper), 
Sideroxylon salicifolium (willow bustic), and Rhus copallinum (winged 
sumac). Short-statured shrubs may include Quercus elliottii (running 
oak), Randia aculeata (white indigoberry), Crossopetalum ilicifolium 
(Christmas berry), Morinda royoc (redgal), and Chiococca alba 
(snowberry).
    Grasses, forbs, and ferns make up a diverse herbaceous layer 
ranging from mostly continuous in areas with more soil development and 
little exposed rock to sparse where more extensive outcroppings of rock 
occur. Typical herbaceous species may include Andropogon spp.; 
Schizachyrium gracile, S. rhizomatum, and S. sanguineum (bluestem 
grasses); Aristida purpurascens (arrowleaf threeawn); Sorghastrum 
secundum (lopsided indiangrass); Muhlenbergia capillaris (hairawn 
muhly); Rhynchospora floridensis (Florida white-top sedge); Tragia 
saxicola (pineland noseburn); Echites umbellata (devil's potato); 
Croton linearis (pineland croton); several species of Chamaesyce spp. 
(sandmats); Chamaecrista fasciculata (partridge pea); Zamia pumila 
(coontie); Anemia adiantifolia (maidenhair pineland fern); Pteris 
bahamensis (Bahama brake); and Pteridium aquilinum var. caudatum (lacy 
bracken) (FNAI 2010a, p. 1).
    There are noticeable differences in species composition between the 
pine rocklands found in the Florida Keys and the mainland. The shrub 
layer in pine rocklands occurring in the northern end of the Miami Rock 
Ridge more closely resembles pine flatwoods as a result of the amount 
of sandy soils in this area, with species such as Lyonia fruticosa 
(staggerbush), Quercus minima (dwarf live oak), Quercus pumila (running 
oak), and Vaccinium myrsinites (shiny blueberry) becoming more common 
(Snyder et al. 1990, p. 255). Pine rocklands in the lower Florida Keys 
have a subcanopy composed of several palms such as Thrinax morrisii, 
Thrinax radiata (Florida thatch palm), and Coccothrinax argentata, and 
hardwoods such as Byrsonima lucida and Psidium longipes (Bradley 2006, 
p. 3). The diversity of the herbaceous layer decreases as the density 
of the shrub layer increases (i.e., as understory openness decreases), 
and pine rocklands on the mainland have a more diverse herbaceous layer 
due to the presence of temperate species and some tropical species that 
do not occur in the Florida Keys (FNAI 2010, p. 63).
    Pine rocklands are maintained by regular fire, and are susceptible 
to other natural disturbances such as hurricanes, frost events, and sea 
level rise (SLR) (Ross et al. 1994). Fires historically burned on an 
interval of approximately every 3 to 7 years, and were typically 
started by lightning strikes during the frequent summer thunderstorms 
(FNAI 2010a, p. 3). Mature South Florida slash pine is highly fire-
resistant (Snyder et al. 1990, p. 259). Above-ground portions of 
hardwood shrubs are typically killed by fire, but often resprout below 
ground; palms typically produce new growth post-fire from their 
unaffected apical buds. The amount of woody understory growth is 
directly related to the length

[[Page 58540]]

of time since the last fire. Herbaceous diversity declines with time 
since last fire. The ecotone between pine rocklands and rockland 
hammock is abrupt when regular fire is present in the system. However, 
when fire is removed, the ecotone becomes more gradual and subtle as 
hardwoods encroach into the pineland (FNAI 2010a, p. 3). If fire is 
excluded for 20 to 30 years, hardwoods will come to dominate the 
community and hammock conditions will prevail, which further discourage 
fires from spreading except in drought conditions. Presently, 
prescribed fire must be periodically introduced into pine rocklands to 
sustain community structure, prevent invasion by woody species, 
maintain high herbaceous diversity (Loope and Dunevitz 1981, pp. 5-6; 
FNAI 2010a, p. 3), and prevent succession to rockland hammock.
    Pine rocklands are also susceptible to natural disturbances such as 
hurricanes and other severe storms, during which trees may be killed, 
thereby helping to maintain the open canopy that is essential to pine 
rocklands plants. During such events, pine rocklands near the coast may 
be temporarily inundated by saltwater, which can also kill or damage 
vegetation (Snyder et al. 1990, p. 251). These sporadic but potentially 
major disturbances, along with burning, create the dynamic nature of 
the pine rocklands habitat. Some currently unsuitable areas may become 
open in the future, while areas currently open may develop more dense 
canopy over time, eventually rendering that portion of the pine 
rocklands unsuitable for pine rocklands endemic plants.
    Within pine rocklands habitat, Chamaecrista lineata var. keyensis 
is associated with areas that have few hardwoods and overstory palms 
are abundant (Bradley and Gann 1999, p 17-18). C. lineata var. keyensis 
plants are often in a clumped distribution surrounded by large areas of 
bare, open rock that do not support plant growth (Bradley 2006, p. 3). 
C. lineata var. keyensis is widespread in pine rocklands of Big Pine 
Key, but more frequent in the northern part of the island (Bradley 
2006, p. 13). It is also more frequent in the interior of pine 
rocklands than on coastal edges (Bradley 2006, p. 13; Bradley and Saha 
2009, p. 9). C. lineata var. keyensis is more abundant in areas with 
relatively higher elevation (Bradley and Saha 2009, p. 26), low shrub 
density, and a diverse herb layer (Bradley 2006, p. 37).
    Roadsides: Roadsides are a potentially important habitat for 
Chamaecrista lineata var. keyensis (Bradley 2006, p. 21). Where pine 
rocklands endemics such as C. lineata var. keyensis are found on road 
shoulders, the ground cover is dominated mostly by native herbs and 
grasses, and exotic lawn grasses have not been planted. Maintaining the 
roadsides in this condition through regular mowing, without planting 
sod, should continue to provide suitable habitat for C. lineata var. 
keyensis (Bradley 2006, p. 37).
Historical Range
    Chamaecrista lineata var. keyensis is endemic to the lower Florida 
Keys in Monroe County, Florida. Historical records exist for 
occurrences on five islands: Big Pine Key, No Name Key, Ramrod Key, 
Cudjoe Key, and Sugarloaf Key (Hodges and Bradley 2006, pp. 20-21).
Current Range, Population Estimates, and Status
    The current range of Chamaecrista lineata var. keyensis is Big Pine 
Key and Cudjoe Key. In 2007, Bradley and Saha (2009, pp. 9-11) surveyed 
Big Pine Key, Cudjoe Key, Little Pine Key, No Name Key, and Sugarloaf 
Key (the five islands in the Florida Keys containing pine rocklands) 
and observed C. lineata var. keyensis only on Big Pine Key and Cudjoe 
Key. It has not been reported from other islands for some time (Ramrod 
Key in 1911, No Name Key in 1916 (Hodges and Bradley 2006, p. 45), and 
Lower Sugarloaf Key in 2005 (Hodges and Bradley 2006, p. 21)). 
Accordingly, C. lineata var. keyensis is considered extirpated from 
Ramrod Key, No Name Key, and Lower Sugarloaf Key--3 of 5 (60 percent) 
of the islands where it was historically recorded (Bradley and Gann 
1999, p. 18; Hodges and Bradley 2006, p. 21). Big Pine Key, Cudjoe Key, 
Little Pine Key, No Name Key, and Sugarloaf Key presently contain pine 
rocklands habitat. No pine rocklands currently exist on Ramrod Key.
    Population data for Chamaecrista lineata var. keyensis have been 
collected periodically on Big Pine Key since 1955. Because of the size 
of Big Pine Key, sample study plots were used, as opposed to a complete 
search of all potential habitat. Multiple indicators show that the 
population on Big Pine Key has declined over the past 60 years (Bradley 
2006, p. 35). Dickson (1955) and Alexander and Dickson (1972) reported 
densities of C. lineata var. keyensis from plots they established on 
Big Pine Key in 1951 and 1969, respectively. Dickson (1955) reports a 
mean density of 10,764 plants/ha (26,599 plants/ac). Alexander and 
Dickson (1972) report a mean density of 27,871 plants/ha (68,872 
plants/ac). In 2005, Bradley (2006, p. 35) recorded 2,339 plants/ha 
(5,780 plants/ac), 23.4 percent and 9.0 percent of the 1955 and 1972 
estimates, respectively. Hurricane Wilma, which passed over Big Pine 
Key on October 24, 2005, generated storm surge in the lower Keys of up 
to 10 feet (Bradley 2006, p. 11; Hodges 2010, p. 4). In 2007, density 
had dropped to 820 plant/ha (2,026 plants/ac) and had not fully 
rebounded after 9 years (Bradley et al. 2015, pp. 21-22). By 2013, 
density had fallen to 657 plants/ha (1,624 plants/ac) (Bradley et al. 
2015, p. 21). In summary, the data from 2005 to 2013 demonstrate a 63.8 
percent decline in the density of C. lineata var. keyensis on Big Pine 
Key (Bradley et al. 2015, p. 48).
    A second indicator, the frequency which Chamaecrista lineata var. 
keyensis occurred in sample plots on Big Pine Key from data collected 
in 2005, 2007, and 2013, also show a decline. Chamaecrista lineata var. 
keyensis was present in 37 percent of plots in 2005, and 19 percent of 
plots in 2013, respectively. This represents a 49 percent reduction in 
the species frequency in study plots (Bradley et al. 2015, p. 48).
    A third indicator, total population size for Chamaecrista lineata 
var. keyensis on publicly owned pine rocklands on Big Pine Key (478 ha 
(1,181 ac)), was estimated to be 866,659 plants in 2005 (pre-Hurricane 
Wilma), 391,944 in 2007 (2 years post-Wilma), and 313,914 in 2013 (8 
years post-Wilma). This represents a population decrease of 64 percent 
(Bradley et al. 2015, p. 21).
    The most recent estimate (2013) of the Chamaecrista lineata var. 
keyensis population on Big Pine Key is 313,914 plants (Bradley et al. 
2015, p. 21). Since 82 percent of the pine rocklands on Big Pine Key 
are publicly owned, this estimate likely accounts for the majority of 
the population. The most recent estimate of the population on Cudjoe 
Key is 150 plants (Hodges and Bradley 2006, p. 21).
    The decline in Chamaecrista lineata var. keyensis can be largely 
attributed to loss of pine rocklands habitat to development and 
modification of this habitat due to inadequate fire management. Folk 
(1991, p. 188) estimated that pine rocklands historically covered 1,049 
ha (2,592 ac), about 44 percent of Big Pine Key. Pine rocklands now 
cover approximately 582 ha (1,438 ac) of Big Pine Key, 56 percent of 
the historical estimate by Folk (1991) (Bradley 2006, p. 4). Hurricanes 
and associated storm surge have also impacted population levels. These 
factors are discussed in detail below,

[[Page 58541]]

under Summary of Biological Status and Threats.

    Table 1--Summary of the Status and Trends of the Known Occurrences of Chamaecrista lineata var. keyensis
----------------------------------------------------------------------------------------------------------------
                                                       Most recent
           Population                Ownership          population           Status                Trend
                                                         estimate
----------------------------------------------------------------------------------------------------------------
Big Pine Key...................  USFWS,\1\ FWC \2\  313, 914 (2014)    Extant \4\.......  Declining.\4\
                                  Monroe County,     \4\.
                                  private.
Cudjoe Key.....................  USFWS,\1\ FWC \2\  150 (2005) \3\...  Extant \3\.......  Insufficient data.
Lower Sugar Loaf Key...........  USFWS,\1\ FWC      3 (2005) \3\.....  Extirpated \3\...
                                  \2\, Monroe
                                  County.
No Name Key....................  unknown..........  no data (1916)     Extirpated \3\...
                                                     \3\.
Ramrod Key.....................  unknown..........  no data (1911)     Extirpated \3\...
                                                     \3\.
----------------------------------------------------------------------------------------------------------------
\1\ U.S. Fish and Wildlife Service.
\2\ Florida Fish and Wildlife Conservation Commission.
\3\ Hodges and Bradley 2006, p. 45.
\4\ Bradley et al. 2015, p. 21.

Biology
    The reproductive biology and relationship to fire of Chamaecrista 
lineata var. keyensis has received a considerable amount of study. 
Significant findings are summarized below.
    Life History and Reproduction: Chamaecrista lineata var. keyensis 
is a perennial, but some stems will die back every year, and a small 
proportion of plants may go dormant for a year or more. Peak flowering 
and fruiting occurs in the summer from May to August, corresponding 
with increased rainfall during these months in the Florida Keys. Mature 
seedpods may contain 1 to 10 seeds. Seedlings may appear throughout the 
year, with a peak in the fall during September to October, immediately 
following seed dispersal. Seeds may persist in the soil seed bank for 
up to 3 years (Liu and Menges 2005, p. 1484).
    Chamaecrista lineata var. keyensis flowers require insect 
visitation for pollination. The anthers (pollen-bearing structures) 
have small pores from which pollen escapes when a visiting insect's 
wings vibrate the structure, a phenomenon known as buzz-pollination. 
Though many types of insects visit C. lineata var. keyensis flowers, 
effective pollination can be performed only by buzz-pollinating bees. 
Of the numerous bee species that visit the flowers, only Xylocopa 
micans and Melissodes spp. bees have been observed performing effective 
buzz-pollination (Liu and Koptur 2003, pp. 1184-1186).
    Chamaecrista lineata var. keyensis flowers are self-compatible (an 
individual can be fertilized with its own pollen), and seeds are 
generated both by self- and cross-pollination. However, seed set is 
higher when cross-pollination occurs. Seed germination rates are higher 
from cross-pollinated flowers, suggesting that inbreeding depression 
occurs in seeds produced through self-pollination (Liu and Koptur 2003, 
pp. 1184-1186). Taken together, these findings confirm that insect 
pollination is crucial to the plant's reproduction and progeny fitness.
    Fire Ecology and Demography: Chamaecrista lineata var. keyensis 
grows in the understory of pine rocklands, a fire-dependent ecosystem. 
The seeds have a hard seed coat that may help them survive fire (Liu et 
al. 2005a, p. 216). Fire has important effects on survival and 
regeneration of C. lineata var. keyensis. Fire may immediately kill 
some of the plants, but populations rebound during the first and second 
years after fire. Three years post-fire, survival in burned areas can 
equal that of unburned areas, suggesting that C. lineata var. keyensis 
can recover completely after fire. Fire stimulates stem growth, 
fruiting, and seedling establishment. Fire seasonality may produce 
different responses in C. lineata var. keyensis. Overall, winter and 
early summer fires produce more favorable results compared with late 
summer fires (Liu and Menges 2005, p. 1848).
    Demographic modeling by (Liu et al. 2005a, p. 210) found that fire 
return intervals of 5 to 7 years generated the lowest extinction and 
population decline probabilities for Chamaecrista lineata var. 
keyensis, regardless of burn season. Bradley and Saha (2009, p. 20) 
found that both fire frequency and time since the last fire had 
significant effects on the density of C. lineata var. keyensis in study 
plots. The highest densities were found in plots that were burned three 
or more times over a 45-year period from 1960 to 2005, and in plots 
that had burned recently, while lower densities were associated with 
plots that had not been burned in 45 years.
    Liu et al. (2005b, p. 71) found that differences in fire intensity 
(as measured by maximum ground temperature) did not have a significant 
long-term effect on survival, growth, or seedling recruitment. However, 
the number of fruits produced and percentage of fruiting plants 
increased as fire intensity increased. This suggests that low-intensity 
fires associated with shorter fire return intervals (less than 3 years) 
may not provide the most favorable conditions for post-fire recovery.
    Taken together, these results indicate that Chamaecrista lineata 
var. keyensis can tolerate and may benefit from periodic fire. As 
discussed above under ``Habitat,'' fire is a crucial element in 
maintaining the pine rocklands habitat. Periodic fires eliminate the 
shrub subcanopy, remove litter from the ground, recycle nutrients, and 
are necessary to prevent succession to a hardwood-dominated ecosystem 
(rockland hammock) that is unsuitable for C. lineata var. keyensis 
(Bradley and Gann 1999, pp. 17-18).
Chamaesyce deltoidea ssp. serpyllum (wedge spurge)
Species Description
    Chamaesyce deltoidea ssp. serpyllum is a small, prostrate, 
perennial herb. The stems are slender and numerous, radiating out from 
the taproot. The leaves are 2 to 5 mm (0.08 to 0.19 in) long, more or 
less triangular, and covered with fine short fuzz, giving the plant a 
silvery appearance. The flowers are cyathia, the specialized 
inflorescences characteristic of the genus Euphorbia and its close 
relatives. The fruit is a capsule about 1.5 mm (0.06 in) wide (Small 
1933, p. 795; Herndon 1993, p. 50).

[[Page 58542]]

Taxonomy
    John K. Small collected plants on Big Pine Key and first described 
Chamaesyce deltoidea ssp. serpyllum as C. serpyllum (Small 1913, p. 
81). Burch (1966, p.99) included C. serpyllum as a subspecies of C. 
deltoidea, assigning the currently accepted name C. deltoidea ssp. 
serpyllum. The online Atlas of Florida Vascular Plants uses the name C. 
deltoidea ssp. serpyllum (Wunderlin and Hansen 2008, p. 1), and the 
Integrated Taxonomic Information System (ITIS 2015, p. 1) indicates 
that its taxonomic status is accepted. We have carefully reviewed all 
taxonomic data to determine that Chamaesyce deltoidea (Engelm. ex 
Chapm.) Small ssp. serpyllum (Small) D.G. Burch is a valid taxon. 
Synonyms include Chamaesyce serpyllum Small; Euphorbia deltoidea 
Engelmann ex Chapman ssp. serpyllum (Small) Y. Yang; and Chamaesyce 
serpyllum Small, Euphorbia deltoidea Engelmann ex Chapman var. 
serpyllum (Small) Oudejans (Wunderlin and Hansen 2008, p. 3).
Climate
    The climate of south Florida where Chamaesyce deltoidea ssp. 
serpyllum occurs is classified as tropical savanna, as described above 
for Chamaecrista lineata var. keyensis.
Habitat
    Chamaesyce deltoidea ssp. serpyllum occurs in pine rocklands and 
adjacent disturbed sites on Big Pine Key, including roadsides. It most 
often grows directly from crevices in the oolitic limestone substrate 
(Bradley and Gann 1999, p. 31). Pine rocklands are described in detail 
for Chamaecrista lineata var. keyensis, above. Within pine rocklands, 
Chamaesyce deltoidea ssp. serpyllum is associated with areas of 
relatively higher elevation, extensive exposed rock substrate, where 
the understory is open, hardwood and palm density is low, and native 
herbaceous species cover and richness are high (Bradley and Saha 2009, 
p. 26; Ross and Ruiz 1996, p. 6; Bradley 2006, p. 27). Roadsides 
dominated mostly by native herbs and grasses where exotic lawn grasses 
are not established are a potentially important habitat for C. 
deltoidea ssp. serpyllum (Bradley 2006, p. 37).
Historical Range
    Chamaesyce deltoidea ssp. serpyllum is historically known from only 
Big Pine Key in the Florida Keys in Monroe County, Florida.
Current Range, Population Estimates, and Status
    The current range of Chamaesyce deltoidea ssp. serpyllum is on Big 
Pine Key. Small groups of plants are scattered widely across the island 
(Herndon 1993, in Bradley and Gann 1999, p. 31).
    Population data for Chamaesyce deltoidea ssp. serpyllum have been 
collected on Big Pine Key periodically since 1996. Indicators show that 
the population on Big Pine Key has declined over the past 19 years. 
Using study plots across Big Pine Key, Ross and Ruiz (1996, p. 6) found 
C. deltoidea ssp. serpyllum was present in 22 percent of study plots in 
1996. When sampled again by Bradley (2006, p. 11; Bradley et al. 2015, 
p. 21) in 2005, 2007, and 2013, the species was present in 7.4, 5.5, 
and 3.7 percent of study plots, respectively. This represents an 83 
percent reduction of the species' frequency in study plots from 1996 to 
2013, and a 50 percent reduction from 2005 to 2013. The decrease in 
frequency is attributed in large part to the total disappearance of the 
species from study plots in the southern portion of Big Pine Key after 
Hurricane Wilma in 2005 (Bradley et al. 2013, p. 24).
    Total population size for Chamaesyce deltoidea ssp. serpyllum on 
publicly owned pine rocklands on Big Pine Key (478 ha (1,181 acres)) 
was estimated to be 352,993 plants in 2005 (pre-Hurricane Wilma), 
343,255 in 2007 (post-Wilma), and 368,557 in 2013. This represents a 
slight (4.4 percent) increase in the known population size of from 2005 
to 2013 (Bradley et al. 2013, p. 21). The slight increase in 2013 is 
due to the Blue Hole Fire in 2011. Prior to this fire, the species had 
not been detected in plots in the Blue Hole area of Big Pine Key, but 
was found in one plot after the 2011 fire. This single plot contained 
134 plants, 17.3 percent of the plants recorded across all 646 plots in 
2013. If this single plot is taken out of the analysis, density per 
plot would be 1.3, 10.3 percent lower than that recorded in 2005, and 
18.6 percent lower than 2007 (Bradley et al. 2015, pp. 24-25; Bradley 
and Saha 2009, p. 12). Since 82 percent of the pine rocklands on Big 
Pine Key are publicly owned, this estimate likely accounts for the 
majority of the population. Taken together, the data suggest that the 
population declined significantly due to Hurricane Wilma but rebounded 
by 2013. However, the frequency of the plant in study plots has 
decreased from 1996 to 2013, suggesting that fewer areas now support 
the species. While there have been significant changes between sampling 
events, the 9-year pattern of total population size is stable (Bradley 
et al. 2015, pp. 21, 24, 49). At the same time, there has been a 
reduction in the species' range on Big Pine Key and frequency of the 
plant in study plots (Bradley et al. 2015, pp. 25, 49), suggesting that 
while there has been a small increase in the total number of plants, 
the area occupied by the plant is shrinking.
    Table 2 summarizes the status and trends of the known occurrences 
of Chamaesyce deltoidea ssp. serpyllum.

    Table 2--Summary of the Status and Trends of the Known Occurrences of Chamaesyce deltoidea ssp. serpyllum
----------------------------------------------------------------------------------------------------------------
                                                       Most recent
           Population                Ownership          population           Status                Trend
                                                         estimate
----------------------------------------------------------------------------------------------------------------
Big Pine Key...................  USFWS, FWC,        368,557 \1\......  Extant \1\.......  Declining.\1\
                                  private.
----------------------------------------------------------------------------------------------------------------
\1\ Bradley et al. 2015, pp. 24-25.

Biology
    Life History and Reproduction: Reproduction is sexual, and the 
plant produces seeds. No studies of reproductive biology or ecology 
have been conducted for Chamaesyce deltoidea ssp. serpyllum. Other 
species of Chamaesyce are completely reliant on insects for pollination 
and seed production, while others are capable of self-pollination. 
Pollinators may include bees, flies, ants, and wasps (Ehrenfeld 1976, 
pp. 406, 95-97).
    Fire Ecology and Demography: The assemblage of endemic plants of 
the pine rocklands, which includes Chamaesyce deltoidea ssp. serpyllum, 
tends to be shade-intolerant and benefits from periodic burning to 
reduce competition from woody vegetation

[[Page 58543]]

(e.g., shading, leaf litter accumulation) (Carlson et al. 1993, p. 922; 
Liu et al. 2005a, p. 210, Liu et al. 2005b, p. 71). C. deltoidea ssp. 
serpyllum is found more frequently in recently burned areas (Slapcinsky 
et al. 2010, p. 11). Populations of C. deltoidea ssp. serpyllum may 
decline without periodic fires, and fire has been shown to stimulate 
significant population growth (Slapcinsky and Gordon 2007, p. 5).
Linum arenicola (sand flax)
Species Description
    Linum arenicola is a small, perennial herb that is 35 to 53 cm (14 
to 21 in) tall with yellow flowers that are similar in appearance those 
of a buttercup (Ranunculus spp.). When not in flower, it resembles a 
short, wiry grass. Plants have one to several stems arising from their 
base. Leaves are linear in shape, 7-10 millimeters (mm) (0.3-0.4 in) 
long, 0.6-1 mm (0.02-0.04 in) wide, and arranged alternately along 
stems, and they have glands scattered along their edges. Flowers are 
produced on stems consisting of a few slender, spreading branches. The 
individual flowers are on small stalks 2 mm (0.08 in) long or shorter. 
The flowers have five yellow, egg-shaped petals that are 4.5-5.5 mm 
(0.18-0.22 in) long, and five green, lance-shaped to egg-shaped sepals 
that are 2.4-3.2 mm (0.09-0.13 in) long. The fruit is a woody capsule, 
2.1-2.5 mm (0.08-0.1 in) long, 2-2.3 mm (0.08-0.09 in) diameter, which 
dries and splits into 10 segments. The seeds are ovate, 1.2-1.4 mm 
(0.05-0.06 in) long, and 0.7- 0.8 mm (0.027-0.031 in) wide (Rogers 
1963, pp. 103-104).
Taxonomy
    Linum arenicola was first described by Small in 1907 as 
Cathartolinum arenicola from plants he collected in Miami-Dade County 
in 1904. This treatment was consistently followed by Small (1913a, p. 
69; 1913b, p. 96; 1933, p. 752). In 1931, Winkler included 
Cathartolinum within the genus Linum, renaming the plants Linum 
arenicola (Winkler 1931, p. 30). Others have followed this treatment, 
including Rogers (1963, p. 103), Long and Lakela (1971, p. 505), 
Robertson (1971, p. 649), Wunderlin (1998, p. 100), and Wunderlin & 
Hansen (2003, p. 100) (Hodges and Bradley 2006, p. 37).
    Synonyms include Cathartolinum arenicola Small (Wunderlin and 
Hansen 2004, p. 5). The Integrated Taxonomic Information System (2015, 
p. 1) uses the name Linum arenicola and indicates that this species' 
taxonomic standing is accepted. The online Atlas of Florida Vascular 
Plants (Wunderlin and Hansen 2008, p. 1) uses the name L. arenicola. 
There is consensus that L. arenicola is a distinct taxon. We have 
carefully reviewed the available taxonomic information to reach the 
conclusion that the species is a valid taxon.
Climate
    The climate of south Florida where Linum arenicola occurs is 
classified as tropical savanna, as described above for Chamaecrista 
lineata var. keyensis and Chamaesyce deltoidea ssp. serpyllum.
    Rainfall within the range of Linum arenicola varies from an annual 
average of 153-165 cm (60-65 in) in the northern portion of the Miami 
Rock Ridge to an average of 89-102 cm (35-40 in) in the lower Florida 
Keys (Snyder et al. 1990, p. 238).
Habitat
    Pine Rocklands: Linum arenicola occurs in pine rocklands, disturbed 
pine rocklands, dry marl prairie, and disturbed areas on rocky soils 
adjacent to these habitats (Bradley and Gann 1999, p. 61; Hodges and 
Bradley 2006, p. 37). L. arenicola grows in thin soil over limestone or 
in small soil patches caught in surface irregularities of exposed 
limestone (Kernan and Bradley, 1996, p. 2). Sites most likely to 
support L. arenicola have a grass- and herb-dominated understory, 
abundant pine regeneration, and high cover of exposed rock (Ross and 
Ruiz 1996, pp. 5-6). The pine rocklands and marl prairies where this 
species occurs require periodic fire to maintain an open, shrub-free 
subcanopy, and to reduce litter levels (Bradley and Saha 2009, p. 4). 
Pine rocklands habitat is described in detail for Chamaecrista lineata 
var. keyensis, above.
    Roadsides and Other Disturbed Sites: While pine rocklands 
historically were the primary habitat of Linum arenicola, the species 
is currently rare in relatively undisturbed pine rocklands, with the 
exception of plants on Big Pine Key. Several occurrences are in scraped 
(scarified) pine rocklands remnants that are dominated by native pine 
rocklands species, but have little or no pine canopy or subcanopy 
(Bradley and Van Der Heiden 2013, pp. 9-12). Two populations in Miami-
Dade County occur entirely on levees composed of crushed oolitic 
limestone that are surrounded by sawgrass marsh (Bradley and Gann 1999, 
p. 61; Bradley and Van Der Heiden 2013, pp. 7-9). Roadsides and other 
disturbed sites are important habitat for L. arenicola because they 
imitate upland herbaceous habitat (Hodges and Bradley 2006, p. 40). The 
most robust roadside populations occur in areas adjacent to pine 
rocklands or rockland hammocks (Hodges 2010, p. 3). Where L. arenicola 
is found on roadsides, the ground cover is dominated mostly by native 
herbs and grasses where exotic lawn grasses have not been planted 
(Bradley 2006, p. 37). Infrequent mowing of some roadsides, and of 
disturbed sites such as Homestead Air Reserve Base (HARB) and U.S. 
Special Operations Command South Headquarters (SOCSOUTH), a unified 
command of all four services in the Department of Defense (DOD) has 
likely allowed the species to persist by preventing these sites from 
being taken over by hardwoods.
    Because Linum arenicola seems to only rarely occur within intact 
pine rocklands, but more frequently adjacent to this habitat, 
developing conservation and management plans for this species is 
exceptionally difficult. Its persistence on roadsides is not fully 
understood. L. arenicola was at one time more common in pine rocklands 
in Miami-Dade County, but a lack of periodic fires in most pine 
rocklands fragments over the last century have pushed this species into 
more sunny, artificial environments (Bradley and Gann 1999, p. 61). It 
is also possible that the species has evolved to persist along 
roadsides as fire regimes and natural areas were altered and destroyed 
over the last century (Hodges and Bradley 2006, p. 41).
    Dry Marl Prairie: Marl prairie is a sparsely vegetated, grass-
dominated community found on marl substrates in South Florida. Marls 
are fine, white, calcareous muds formed from calcite precipitated by a 
mixture of green algae, blue green algae, and diatoms, known as 
periphyton. It is seasonally inundated (2 to 4 months) to a shallow 
depth averaging about 20 cm (8 in). Marl prairie is a diverse community 
that may contain over 100 species. Marl prairie normally dries out 
during the winter and is subject to fires at the end of the dry season 
(FNAI 2010, p. 1). Occurrences reported from marl prairie are at sites 
that have been artificially drained (Bradley and Van Der Heiden 2013, 
p. 11), or are scraped pine rocklands that function more like marl 
prairie (Kernan and Bradley 1996, p. 11). As with roadside populations 
of Linum arenicola, it is possible that dry marl prairies have become 
refugia for the species as fire regimes and natural areas were altered 
and destroyed over the last century. Accordingly, the Service does not 
consider marl prairie to be a primary habitat for L. arenicola.
Historical Range
    The historical range of Linum arenicola consists of central and 
southern Miami-Dade County and

[[Page 58544]]

Monroe County in the lower Florida Keys (Bradley and Gann 1999, p. 61). 
In Miami-Dade County, records for the species were widespread from the 
Coconut Grove area to the southern part of the County, close to what is 
now the main entrance to Everglades National Park and Turkey Point 
(Bradley and Gann 1999, p. 61). In the Florida Keys (Monroe County), 
there are records of the species from Big Pine Key, Ramrod Key, Upper 
and Lower Sugarloaf Keys, Park Key, Boca Chica Key, Middle Torch Key 
(Bradley and Gann 1999, p. 61), and Big Torch Key (Hodges 2010, p. 10).
Current Range, Population Estimates, and Status
    The current range of Linum arenicola consists of eight extant 
populations in Miami-Dade County and four extant populations in the 
Florida Keys (see Table 3, below). In Miami-Dade County, the current 
distribution of Linum arenicola is from just north of SW 184 Street (in 
the Richmond Pinelands), south to the intersection of Card Sound Road 
and the C-102 canal, and west to SW 264 Street and 177 Avenue 
(Everglades Archery Range at Camp Owaissa Bauer). This distance is 
approximately 30 km (19 mi) north to south, and 14 km (9 mi) east to 
west. In the Florida Keys (Monroe County), the current distribution of 
L. arenicola includes four islands: Big Pine Key, Upper and Lower 
Sugarloaf Keys, and Big Torch Key.
    Multiple surveys have been conducted for Linum arenicola in Miami-
Dade and Monroe Counties over the past 30 years. However, most surveys 
only cover one county and not the other. The large area of potential 
habitat and scarcity and diminutive size of L. arenicola make thorough 
surveys for this species difficult (Hodges and Bradley 2006, p. 37).
    Based on a compilation of all survey work through 2013, including 
Austin (1980), Kernan and Bradley (1996, pp.1-30), Bradley and Gann 
(1999, pp. 61-65), Hodges and Bradley (2006, pp. 37-41), Bradley and 
Saha (2009, p. 10), Bradley (2009, p. 3), Hodges (2010, pp. 4-5, 15), 
Bradley and van der Heiden (2013, pp. 6-12,19), and Bradley et al. 
(2015, pp. 28-29), of 26 historical population records for Linum 
arenicola, 12 populations are extant and 14 are extirpated (see Table 
3), a loss of roughly 54 percent of known populations, from the early 
1900s to the present.
    Table 3 summarizes the status and trends of the known occurrences 
of Linum arenicola.

              Table 3--Summary of the Status and Trends of the Known Occurrences of Linum arenicola
----------------------------------------------------------------------------------------------------------------
                                                          Most recent
           Population                  Ownership          population            County               Trend
                                                           estimate
----------------------------------------------------------------------------------------------------------------
                                                Extant 12 records
----------------------------------------------------------------------------------------------------------------
Big Pine Key....................  USFWS, FWC, TNC     2,676 (2007) \1\..  Monroe............  declining.
                                   \12\, Private.
Upper Sugarloaf Key.............  FDOT \13\, USFWS..  73 (2010) \2\.....  Monroe............  insufficient data.
Lower Sugarloaf Key.............  FDOT \13\, USFWS..  531 (2010) \2\....  Monroe............  stable.
Big Torch Key...................  FDOT \13\, Private  1 (2010) \2\......  Monroe............  declining.
Richmond Pineland...............  Private...........  56 (2014) \5\.....  Miami-Dade........  insufficient data.
Martinez Pineland...............  Miami-Dade County.  100-200 (2013) \6\  Miami-Dade........  insufficient data.
Everglades Archery Range (Camp    Miami-Dade County.  23 (2012) \7\.....  Miami-Dade........  insufficient data.
 Owaissa Bauer).
HAFB \15\ 1--S of Naizare BLVD..  DOD \14\, Miami-    24,000 (2013) \7\.  Miami-Dade........  stable.
                                   Dade County.
SOCSOUTH (HAFB 2--NW side of      DOD \14\ (leased    74,000 (2009) 7 10  Miami-Dade........  stable.
 Bikini BLVD).                     from Miami-Dade
                                   County).
HARB (SW 288 St. and 132 Ave)...  DOD \14\..........  37 (2011) \7\.....  Miami-Dade........  insufficient data.
C-102 Canal SW 248 St. to U.S. 1  SFWMD \11\........  1,000-10,000        Miami-Dade........  insufficient data.
                                                       (2013) \7\.
L-31E canal, from SW 328 St. to   SFWMD \11\........  Plants occur along  Miami-Dade........  insufficient data.
 Card Sound Road.                                      14 km (8.7 mi) of
                                                       levee (2013) \7\.
----------------------------------------------------------------------------------------------------------------
                                              Extirpated 14 records
----------------------------------------------------------------------------------------------------------------
Middle Torch Key................  FWC, FDOT \13\....  3 (2005) \3\......  Monroe............
Ramrod Key......................  FDOT \13\.........  110 (1979) \4\....  Monroe............
Park Key........................  FDOT \13\.........  unknown (1961) \3\  Monroe............
Boca Chica......................  DOD \14\, other     unknown (1912) \3\  Monroe............
                                   (unknown).
Camp Jackson....................  unknown...........  unknown (1907) \9\  Miami-Dade........
Big Hammock Prairie.............  unknown...........  unknown (1911) \9\  Miami-Dade........
Camp Owaissa Bauer..............  Miami-Dade County.  10 (1983) \7\.....  Miami-Dade........
Allapatah Drive and Old Cutler    Private...........  256 (1996) \8\....  Miami-Dade........
 Road.
Bauer Drive (Country Ridge        Miami-Dade County.  8 (1996) \8\......  Miami-Dade........
 Estates).
Silver Green Cemetery...........  Private...........  47 (1996) \8\.....  Miami-Dade........
Palmetto Bay Village Center.....  Private...........  12 (1996) \8\.....  Miami-Dade........
HAFB (Community Partnership       DOD \14\, Miami-    unknown (2010) \7\  Miami-Dade........
 Drive).                           Dade County.
Coco Plum Circle (corner of       Private...........  75 (1996) \8\.....  Miami-Dade........
 Robles Street & Vista Mar
 Street).

[[Page 58545]]

 
George Avery Pineland Preserve..  Private...........  ``small colony''    Miami-Dade........
                                                       (2002) \7\.
----------------------------------------------------------------------------------------------------------------
\1\ Bradley and Saha 2009, p. 10
\2\ Hodges 2010, p. 10
\3\ Hodges and Bradley 2006, pp. 39-48
\4\ Austin et al. 1980 in FNAI
\5\ FTBG 2014, p. 2
\6\ Possely 2014, pers. comm.
\7\ Bradley and Van Der Heiden 2013, pp. 6-11
\8\ Kernan and Bradley 1996, p. 9
\9\ Bradley and Gann 1999, p. 65
\10\ Bradley 2009, p. 3
\11\ South Florida Water Management District (SFWMD)
\12\ The Nature Conservancy (TNC)
\13\ Florida Department of Transportation (FDOT)
\14\ Department of Defense (DOD)
\15\ Homestead Air Force Base (HAFB; decommissioned)

    Based on the data presented in Table 3, reliable population trends 
can be derived from past surveys for 5 of the 12 extant populations. 
Populations on Big Pine Key and Big Torch Key have shown clear 
declines. Three populations appear to be stable (data suggest they have 
not declined appreciably). Data are insufficient to determine trends 
for the remaining seven populations. The data also show that 5 of the 
12 extant populations are rather small, having fewer than 100 plants.
    Miami-Dade County: The first survey for Linum arenicola, conducted 
in 1980 in Miami-Dade County, reported two extant and eight extirpated 
populations, but population sizes were not reported (Austin et al., 
1980, p. 3). A 1996 survey conducted in Miami-Dade County reported 
seven populations, representing about 1,000 plants (Kernan and Bradley 
1996, p. 5). A 1999 status survey reported five extant populations and 
seven extirpated populations in Miami-Dade County (Bradley and Gann 
1999, p. 65).
    A comprehensive field survey of Linum arenicola sites in Miami-Dade 
was conducted in 2013 (Bradley and van der Heiden 2013, p. 4). L. 
arenicola populations were found at six sites, containing an estimated 
total of 107,060 plants. Populations ranged in size from 23 plants to 
74,000 plants, with a median population size of approximately 4,500. 
All but one of the Miami-Dade L. arenicola populations occur on public 
lands, but only the Martinez Pineland site is managed for conservation. 
The remaining sites are owned by the DOD (military bases), State of 
Florida (canal banks; SFWMD), and Miami-Dade County (a public archery 
range). A seventh small population located in 2014 at the Richmond 
pinelands is located on private land that is currently slated for 
development (Fairchild Tropical Botanic Garden (FTBG) 2014, p. 2). The 
largest Linum arenicola population in Miami-Dade County, estimated at 
74,000 plants in 2009 (Bradley 2009, p. 3), is located on property 
owned by the Miami-Dade County Homeless Trust and leased to Special 
Operations Command South (SOCSOUTH; a DOD facility).
    In Miami-Dade County, of 18 records for Linum arenicola, 8 
populations are extant, while 10 are extirpated, a loss of roughly 56 
percent of known populations. The loss of these populations corresponds 
to a contraction of the species' historical range in Miami-Dade County 
by approximately 20 km (12 mi) at its northern extent (40 percent 
reduction in north to south range), and approximately 15 km (9 mi) of 
its east to west extent (50 percent reduction in east to west range).
    Monroe County (Florida Keys): A 1999 status survey reported four 
Linum arenicola populations in Monroe County (Bradley and Gann 1999, p. 
65). In 2006, Hodges and Bradley (2006, pp. 37-41) conducted the first 
comprehensive survey of the distribution and abundance of L. arenicola 
in the Florida Keys, including extant occurrences, historical records, 
and exploratory surveys of potential habitat. Four extant populations 
were observed (Big Pine Key, Big Torch Key, Middle Torch Key, and Lower 
Sugarloaf Key) and three historical populations were confirmed 
extirpated (Boca Chica Key, Ramrod Key, and Park Key). The surveys did 
not find L. arenicola in potential habitat on No Name Key, Little Torch 
Key, or Upper Sugarloaf Key (Hodges and Bradley 2006, pp. 37, 48). 
However, in 2010, Hodges (2010, p. 10) resurveyed Upper Sugarloaf and 
rediscovered the population.
    Linum arenicola is extirpated from 4 of 8 (50 percent) of the 
islands that once supported it. Its historical range spanned 
approximately 36 km (22 mi) from northeast to southwest. The loss of 
populations on Boca Chica, Park, Middle Torch, and Ramrod Keys 
represents a 14-km (9-mi) loss of the western extent of the species' 
range, corresponding to a 39 percent contraction of the species' 
historical range.
    The total population of Linum arenicola in Monroe County is 
estimated at 2,676 plants in pine rocklands on Big Pine Key (Bradley 
and Saha 2009, p. 10), and 100 to 1,000 plants across the remainder of 
the Florida Keys (Hodges and Bradley 2006, pp. 37, 48; Hodges 2010, p. 
10).
    The largest population in Monroe County is located on Big Pine Key 
within the National Key Deer Refuge (NKDR) and surrounding lands, where 
there are approximately 478 ha (1,181 ac) of publicly owned pine 
rocklands (Gann et al. 2002, p. 806; Bradley 2006, p. 4; Hodges and 
Bradley 2006, pp. 37-38). It is also the best studied population. On 
Big Pine Key, Linum arenicola occurs at the Terrestris Preserve, which 
is owned by TNC; this occurrence is included within the Big Pine Key 
site in Table 3.
    Linum arenicola on Big Pine Key has been surveyed multiple times 
since 1996, with the most recent being 2014. Because of the size of Big 
Pine Key, sample study plots were utilized for these surveys, as 
opposed to a complete search of all potential habitats. Ross and Ruiz 
(1996, p. 5) found the species in 11 percent of their study plots. 
Subsequent surveys in 2005, 2007, and 2013 have found L. arenicola to 
be extremely rare, being recorded in 4.1, 2.0, and 1.4

[[Page 58546]]

percent of study plots, respectively, representing an 87 percent 
reduction from 1996 to 2013 (Bradley et al. 2015, pp. 28-29).
    The decline in the Big Pine Key population of Linum arenicola from 
2005 to 2007 can be largely attributed to the effects of Hurricane 
Wilma (Bradley 2006, p. 11; Hodges 2010, p. 4). Prior to Wilma, there 
was a maximum of 56,404 individuals of L. arenicola in the 478 ha 
(1,181 ac) of publicly owned pine rocklands on Big Pine Key (Bradley 
2006, p. 19). As of 2007, there were just 2,676 plants, representing a 
95 percent decline (Bradley and Saha 2009, p. 10). Significantly, the 
species virtually disappeared from the southern half of Big Pine Key 
after Hurricane Wilma (Bradley and Saha 2009, p. 10).
    Historically, the population has declined due to habitat loss and 
fire suppression. Approximately half of the historical pine rocklands 
on Big Pine Key have been lost (Bradley 2006, p. 35). Long-term 
ecological changes associated with fire suppression, land clearing, 
SLR, changes in hydrology, fluctuations in Key deer (Odocoileus 
virginianus clavium) densities, and invasion of exotic plants likely 
have impacted the population sizes of this species (Bradley 2006, p. 2; 
Bradley and Saha 2009, p. 2).
    The population on Big Torch Key also declined after Hurricane 
Wilma, but this decline may have been due to herbicide applications or 
frequent mowing associated with road shoulder maintenance (Hodges 2010, 
p. 4).
Biology
    Life History and Reproduction: Little is known about the life 
history of Linum arenicola, including pollination biology, seed 
production, or dispersal. Reproduction is sexual, with new plants 
generated from seeds. The species produces flowers from February to 
September, with a peak around March and April. L. arenicola population 
demographics or longevity have not been studied (Bradley and Gann, 
1999, p. 65; Hodges and Bradley 2006, p. 41; Hodges 2007, p. 2).
    Fire Ecology and Demography: There have been no studies of Linum 
arenicola population demographics or relationship to fire, though 
historical declines have been partially attributed to habitat loss from 
fire suppression or inadequate fire management.
Argythamnia blodgettii (Blodgett's silverbush)
Species Description
    Argythamnia blodgettii, in the Euphorbia family, is an erect, 
perennial shrub or herb, 10 to 60 cm (4 to 24 in) tall, with a woody 
base and small, green flowers. The stems and leaves are covered with 
small hairs. The leaves, arranged alternately along the stems, are 1.5 
to 4.0 cm (0.6 to 1.6 in) long, have smooth (or rarely toothed) edges, 
are oval or elliptic in shape, and often are colored a distinctive, 
metallic bluish green. The plants have separate male and female 
flowers. Staminate (male) flowers have a calyx 7 to 8 mm (0.27 to 0.31 
in) wide, consisting of 4 to 5 lance-shaped sepals that are larger than 
the petals. The petals are broadly elliptic and shorter than the 
sepals. There are 10 stamens. Pistillate (female) flowers have 4 to 5 
sepals that are 5 to 6 mm (0.19 to 0.24 in) long, lance-shaped, and 
often more narrow than those of male flowers. The petals are broadly 
elliptic, shorter than the sepals. The fruit is a woody capsule 4 to 5 
mm (0.16 to 0.19 in) wide, which contains the seeds (Adapted from Small 
1933, pp. 784-785; Bradley and Gann 1999, p. 2).
Taxonomy
    Botanist John Torrey first described the species in Chapman (1884, 
p. 100) as Aphora blodgettii, reporting it for South Florida. In an 
1896 (p. 100) revision of the genus, Pax placed it in the genus 
Ditaxis. In 1897 (p. 100), Chapman placed it in the genus Argythamnia. 
In 1903, Small placed it again in the genus Ditaxis. In 1914, Pax (p. 
100) placed it in synonymy under Ditaxis fendleri, a plant of Colombia, 
Venezuela, Curacao, and Trinidad. Small (1933, pp. 784-785) retained it 
as Ditaxis blodgettii, treating it as a southern Florida endemic. 
Subsequent authors (Webster 1967, p. 100; Long and Lakela 1971, p. 558; 
Wunderlin 1998, p. 100; Wunderlin and Hansen 2003, p. 100) have 
retained it as a southern Florida endemic Argythamnia blodgettii (from 
Hodges and Bradley 2006, p. 10).
    The Integrated Taxonomic Information System (2015, p. 1) uses the 
name Argythamnia blodgettii and indicates that this species' taxonomic 
standing is accepted. The online Atlas of Florida Vascular Plants 
(Wunderlin and Hansen 2008, p. 1) uses the name A. blodgettii. In 
summary, there is consensus that A. blodgettii is a distinct taxon. We 
have carefully reviewed the available taxonomic information to reach 
the conclusion that the species is a valid taxon. Synonyms include 
Aphora blodgettii Torr. ex Chapm.; Ditaxis blodgettii (Torr. ex Chapm.) 
Pax; Argyrothamnia blodgettii (Torr. ex Chapm.) Chapm.; and Ditaxis 
fendleri Pax, not (M[uuml]ll. Arg.) Pax and K. Hoof.
Climate
    The climate of south Florida where Argythamnia blodgettii occurs is 
classified as tropical savanna, as described above for Chamaecrista 
lineata var. keyensis, Chamaesyce deltoidea ssp. serpyllum, and Linum 
arenicola.
    Rainfall within the range of Argythamnia blodgettii varies from an 
annual average of 153-165 cm (60-65 in) in the northern portion of the 
Miami Rock Ridge to an average of 89-102 cm (35-40 in) in the lower 
Florida Keys (Snyder et al. 1990, p. 238).
Habitat
    Argythamnia blodgettii grows in pine rocklands, in sunny gaps or 
edges of rockland hammock and coastal berm, and on roadsides (Bradley 
and Gann 1999, p. 3). It grows from crevices on oolitic limestone or on 
sand. The pine rocklands habitat where it occurs requires periodic fire 
to maintain an open, sunny understory with a minimum amount of 
hardwoods. Bradley and Gann (1999, p. 3) indicated that this species 
does tolerate some degree of human-induced disturbance. It can often be 
found along disturbed edges of pine rocklands, rockland hammock, and 
coastal berm, or in completely scarified pine rocklands (Bradley and 
Gann, 1999, p. 3). Pine rocklands are described in detail for 
Chamaecrista lineata var. keyensis, above.
    Coastal Berm: Coastal berms are landscape features found along low-
energy coastlines in south Florida and the Florida Keys. Coastal berm 
is a short forest or shrub thicket found on long, narrow, storm-
deposited ridges of loose sediment formed by a mixture of coarse shell 
fragments, pieces of coralline algae, and other coastal debris. These 
ridges parallel the shore and may be found on the seaward edge or 
landward edge of the mangroves or farther inland depending on the 
height of the storm surge that formed them. They range in height from 
0.30 to 3.05 m (1 to 10 ft). Structure and composition of the 
vegetation is variable depending on height and time since the last 
storm event. The most stable berms may share some tree species with 
rockland hammocks, but generally have a greater proportion of shrubs 
and herbs. Tree species may include Bursera simaruba (gumbo limbo), 
Coccoloba uvifera (seagrape), Coccothrinax argentata (silver palm), 
Guapira discolor (blolly), Drypetes diversifolia (milkbark), Genipa 
clusiifolia (seven year apple), and Metopium toxiferum (poisonwood). 
Characteristic tall shrub and short tree

[[Page 58547]]

species include Eugenia foetida (Spanish stopper), Ximenia americana 
(hog plum), Randia aculeata (white indigoberry), Pithecellobium keyense 
(Florida Keys blackbead), and Sideroxylon celastrinum (saffron plum). 
Short shrubs and herbs include Hymenocallis latifolia (perfumed 
spiderlily), Capparis flexuosa (bayleaf capertree), Lantana involucrata 
(buttonsage), and Rivina humilis (rougeplant). More seaward berms or 
those more recently affected by storm deposition may support a suite of 
plants similar to beaches, including shoreline Sesuvium portulacastrum 
(sea purslane), Distichlis spicata (saltgrass), and Sporobolus 
virginicus (seashore dropseed), or scattered to dense shrub thickets 
with Conocarpus erectus (buttonwood), stunted Avicennia germinans 
(black mangrove), Rhizophora mangle (red mangrove), Laguncularia 
racemosa (white mangrove), Suriana maritima (bay cedar), Manilkara 
jaimiqui (wild dilly), Jacquinia keyensis (joewood), and Borrichia 
frutescens (bushy seaside oxeye) (Florida Natural Areas Inventory 
(FNAI) 2010a, p. 1).
    Coastal berms are deposited by storm waves along low-energy coasts. 
Their distance inland depends on the height of the storm surge. Tall 
berms may be the product of repeated storm deposition. Coastal berms 
that are deposited far enough inland and remain long-undisturbed may in 
time succeed to hammock. This is a structurally variable community that 
may appear in various stages of succession following storm disturbance, 
from scattered herbaceous beach colonizing plants to a dense stand of 
tall shrubs (FNAI 2010a, p. 2).
    Rockland Hammock: Rockland hammock is a species-rich, tropical 
hardwood forest on upland sites in areas where limestone is very near 
the surface and often exposed. The forest floor is largely covered by 
leaf litter with varying amounts of exposed limestone and has few 
herbaceous species. Rockland hammocks typically have larger, more 
mature trees in the interior, while the margins can be almost 
impenetrable in places with dense growth of smaller shrubs, trees, and 
vines. Typical canopy and subcanopy species include Bursera simaruba, 
Lysiloma latisiliquum (false tamarind), Coccoloba diversifolia (pigeon 
plum), Sideroxylon foetidissimum (false mastic), Ficus aurea (strangler 
fig), Piscidia piscipula (Jamaican dogwood), Ocotea coriacea 
(lancewood), Drypetes diversifolia, Simarouba glauca (paradisetree), 
Sideroxylon salicifolium (willow bustic), Krugiodendron ferreum (black 
ironwood), Exothea paniculata (inkwood), Metopium toxiferum, and 
Swietenia mahagoni (West Indies mahogany). Mature hammocks may be open 
beneath a tall, well-defined canopy and subcanopy. More commonly, in 
less mature or disturbed hammocks, dense woody vegetation of varying 
heights from canopy to short shrubs is often present. Species that 
generally make up the shrub layers within rockland hammock include 
several species of Eugenia (stoppers), Thrinax morrisii and T. radiata 
(thatch palms), Amyris elemifera (sea torchwood), Ardisia 
escallonioides (marlberry), Psychotria nervosa (wild coffee), 
Chrysophyllum oliviforme (satinleaf), Sabal palmetto (cabbage palm), 
Guaiacum sanctum (lignum-vitae), Ximenia americana, Colubrina elliptica 
(soldierwood), Pithecellobium unguis-cati and Pithecellobium keyense, 
Coccoloba uvifera, and Colubrina arborescens (greenheart). Vines can be 
common and include Toxicodendron radicans (eastern poison ivy), Smilax 
auriculata (earleaf greenbrier), Smilax havanensis (Everglades 
greenbrier), Parthenocissus quinquefolia (Virginia creeper), 
Hippocratea volubilis (medicine vine), and Morinda royoc (redgal). The 
typically sparse short shrub layer may include Zamia pumila (coontie) 
and Acanthocereus tetragonus (triangle cactus). Herbaceous species are 
occasionally present and generally sparse in coverage. Characteristic 
species include Lasiacis divaricata (smallcane), Oplismenus hirtellus 
(basketgrass), and many species of ferns (FNAI 2010e, p. 1).
    Rockland hammock occurs on a thin layer of highly organic soil 
covering limestone on high ground that does not regularly flood, but it 
is often dependent upon a high water table to keep humidity levels 
high. Rockland hammocks are frequently located near wetlands; in the 
Everglades, they can occur on organic matter that accumulates on top of 
the underlying limestone; in the Keys, they occur inland from tidal 
flats (FNAI 2010e, p. 1).
    Rockland hammock is susceptible to fire, frost, canopy disruption, 
and ground water reduction. Rockland hammock can be the advanced 
successional stage of pine rocklands, especially in cases where 
rockland hammock is adjacent to pine rocklands. In such cases, when 
fire is excluded from pine rocklands for 15 to 25 years, it can succeed 
to rockland hammock vegetation. Historically, rockland hammocks in 
south Florida evolved with fire in the landscape. Fire most often 
extinguished near the edges when it encountered the hammock's moist 
microclimate and litter layer. However, rockland hammocks are 
susceptible to damage from fire during extreme drought or when the 
water table is lowered. In these cases, fire can cause tree mortality 
and consume the organic soil layer (FNAI 2010e, p. 2).
    Rockland hammocks are also sensitive to the strong winds and storm 
surge associated with infrequent hurricanes. Canopy damage often 
occurs, which causes a change in the microclimate of the hammock. 
Decreased relative humidity and drier soils can leave rockland hammocks 
more susceptible to fire. Rockland hammock can transition into glades 
marsh, mangrove swamp, salt marsh, coastal rock barren, pine rocklands, 
maritime hammock, or marl prairie (FNAI 2010e, p. 2).
    The sparsely vegetated edges or interior portions laid open by 
canopy disruption are the areas of rockland hammock that have light 
levels sufficient to support Argythamnia blodgettii. However, the 
dynamic nature of the habitat means that areas not currently open may 
become open in the future as a result of canopy disruption from 
hurricanes, while areas currently open may develop more dense canopy 
over time, eventually rendering that portion of the hammock unsuitable 
for A. blodgettii.
Historical Range
    Argythamnia blodgettii historically occurred from central and 
southern Miami-Dade County from Brickell Hammock to Long Pine Key in 
Everglades National Park, and in Monroe County throughout the Florida 
Keys from Totten Key south to Key West (Bradley and Gann 1999, p. 2).
Current Range, Population Estimates, and Status
    Argythamnia blodgettii is currently known from central Miami-Dade 
County from Coral Gables and southern Miami-Dade County to Long Pine 
Key in Everglades National Park, and the Florida Keys from nine 
islands, from Windley Key (Bradley and Gann 1999, p. 3) southwest to 
Boca Chica Key (Hodges and Bradley 2006, pp. 10, 43).
    Previous status surveys of Argythamnia blodgettii include Bradley 
and Gann (1999, pp. 2-6) and Hodges and Bradley (2006, pp. 11-20, 43). 
Bradley and Gann (1999, p. 3) reported 18 extant occurrences of A. 
blodgettii in 1999 (4 in Monroe County, 14 in Miami-Dade County), 
representing approximately 10,000 plants. Hodges and Bradley (2006, pp. 
11-20, 43) verified that A. blodgettii is extant on nine islands in the 
Florida Keys

[[Page 58548]]

(Monroe County), and has an estimated population of between 10,000 and 
100,000 plants (Hodges and Bradley, p. 2). The FNAI element tracking 
summary data indicated a total of 31 element occurrence records in 2 
counties, with 24 occurrences in management areas (FNAI 2008, p. 1). 
There is insufficient data available to identify trends in any 
populations of A. blodgettii.
    Although we do not know the total extent of the former range of 
Argythamnia blodgettii, approximately 12 miles (19 kilometers) of the 
species' range has been lost near the northern end of the range in 
Miami-Dade County and 43 miles (69 kilometers) has been lost in Monroe 
County on the southern edge of the species' range (Bradley and Gann 
1999, p. 3).
    Miami-Dade County: According to data from the Institute for 
Regional Conservation (IRC), the estimated population of Argythamnia 
blodgettii in Miami-Dade County is 375 to 13,650 plants (i.e., total of 
low and high estimates) (K. Bradley 2007, pers. comm.); however, this 
may be an overestimate of the actual population size because it was 
based upon a log10 scale. In Everglades National Park (ENP), the 
current estimated population size is 2,000 plants (J. Sadle 2015, pers. 
comm.).
    Based on the data presented below in Table 4, there are 31 records 
for Argythamnia blodgettii in Miami-Dade County. Six populations are 
extant, 11 are extirpated, and the status of 14 is uncertain because 
they have not been surveyed in 15 years or more.
    Monroe County: In the Keys, Argythamnia blodgettii is extant on 
nine islands, with three others of uncertain status (Hodges and Bradley 
2006, p. 43). The largest population surveyed is on Big Munson Island 
and is estimated to be 8,000 to 9,000 plants (Hodges and Bradley 2006, 
p. 17). On Big Pine Key, a population of A. blodgettii estimated at 
2,200 plants is found scattered across the island. Occurrences are 
known from the Koehn's subdivision, Long Beach, Cactus Hammock, and 
Watson Hammock. Sizable populations also occur at Key West Naval Air 
Station on Boca Chica Key. The total population size in the Florida 
Keys is estimated to be approximately 13,200 plants (Hodges and Bradley 
2006, pp. 10-13, 17).
    Argythamnia blodgettii is extirpated from 3 of 16 (23 percent) of 
the islands that once supported it. Based on the data presented in 
Table 4, there are 18 records for A. blodgettii in Monroe County. 
Eleven populations are extant, three are extirpated, and the status of 
four is uncertain because they have not been surveyed in 15 years or 
more.

          Table 4--Summary of the Status and Trends of the Known Occurrences of Argythamnia blodgettii
----------------------------------------------------------------------------------------------------------------
                                                          Most recent
           Population                  Ownership          population            County               Trend
                                                           estimate
----------------------------------------------------------------------------------------------------------------
                                                Extant 17 records
----------------------------------------------------------------------------------------------------------------
Plantation Key, Snake Creek       FWC...............  101-1,000 (2005)    Monroe............  Insufficient data.
 Hammock.                                              \2\.
Lower Matecumbe Key--Klopp Tract  FDEP \6\..........  11-100 (2000) \2\.  Monroe............  Insufficient data.
Lignumvitae Key.................  FDEP \6\..........  101-1,000 (2005)    Monroe............  Insufficient data.
                                                       \2\.
Big Munson Island...............  Private (Boy        1,001-10,000        Monroe............  Insufficient data.
                                   Scouts of           (2005) \2\.
                                   America).
North Key Largo.................  DOD, FDOT.........  No estimate (2005)  Monroe............  Insufficient Data.
                                                       \8\.
Key Largo--Dove Creek Hammock...  FWC, FDOT.........  11-100 (2005) \2\.  Monroe............  Insufficient data.
Vaca Key (Marathon)--Blue Heron   FWC, FDOT.........  11-100 (2005) \2\.  Monroe............  Insufficient data.
 Hammock.
Windley Key--State Park.........  FDEP \6\..........  11-100 (2005) \2\.  Monroe............  Insufficient data.
Boca Chica KWNAS \7\ Runway 25..  DOD...............  1,001-10,000        Monroe............  Insufficient data.
                                                       (2004) \2\.
Boca Chica Key KWNAS \7\ Weapons  DOD...............  200 (2004) \2\....  Monroe............  Insufficient data.
 Hammock.
Big Pine Key....................  USFWS, FWC,         ~2,200 (2005) \2\.  Monroe............  Insufficient data.
                                   private.
ENP Long Pine Key Deer Hammock    NPS \5\...........  2,000 (2015) \4\..  Miami-Dade........  Insufficient data.
 area (Pine Block A), Turkey
 Hammock area (Pine Block B),
 Pine Block E.
Camp Choee......................  Private (Girl       3 (2005) \3\......  Miami-Dade........  Insufficient data.
                                   Scout Council of
                                   Tropical Florida).
Crandon Park--Key Biscayne......  Miami Dade Parks    4 (2005) \3\......  Miami-Dade........  Insufficient data.
                                   and Recreation.
Martinez Pineland/Larry and       Miami Dade Parks    6 (2005) \3\......  Miami-Dade........  Insufficient data.
 Penny Thompson Park.              and Recreation.
Tropical Park Pineland..........  Miami Dade Parks    20 (2005) \3\.....  Miami-Dade........  Insufficient data.
                                   and Recreation.
Boystown Pineland...............  Private...........  No estimate (2005)  Miami-Dade........  Insufficient data.
                                                       \3\.
----------------------------------------------------------------------------------------------------------------
                                              Uncertain 18 records
----------------------------------------------------------------------------------------------------------------
Crawl Key, Forestiera Hammock...  Private...........  10 (1982) \3\.....  Monroe............  Insufficient data.
Long Key State Park.............  FDEP..............  No estimate (1999)  Monroe............  Insufficient data.
                                                       \2\.
Stock Island....................  Private...........  No estimate (1981)  Monroe............  Insufficient data.
                                                       \2\.
Boot Key........................  Private...........  11-100 (1998) \2\.  Monroe............  Insufficient data.
Deering Estate..................  State of Florida..  11-100 (1991) \1\.  Miami-Dade........  Insufficient data.

[[Page 58549]]

 
Castellow Hammock...............  Miami Dade Parks    11-100 (1991) \1\.  Miami-Dade........  Insufficient data.
                                   and Recreation.
Owaissa Bauer County Park.......  Miami Dade Parks    101-1,000 (1991)    Miami-Dade........  Insufficient data.
                                   and Recreation.     \1\.
Pine Ridge Sanctuary............  Private...........  2-10 (1992) \1\...  Miami-Dade........  Insufficient data.
County Ridge Estates............  Private...........  11-100 (1999) \1\.  Miami-Dade........  Insufficient data.
Epmore Drive pineland...........  Private...........  2-10 (1999) \1\...  Miami-Dade........  Insufficient data.
Gifford Arboretum Pineland......  Private...........  2-10 (1999) \1\...  Miami-Dade........  Insufficient data.
Ned Glenn Nature Preserve.......  Miami Dade Parks    11-100 (1999) \1\.  Miami-Dade........  Insufficient data.
                                   and Recreation.
Natural Forest Community #317...  Private...........  2-10 (1999) \1\...  Miami-Dade........  Insufficient data.
Old Dixie pineland..............  Private...........  11-100 (1999) \1\.  Miami-Dade........  Insufficient data.
Owaissa Bauer Addition #1.......  Miami Dade Parks    11-100 (1991) \1\.  Miami-Dade........  Insufficient data.
                                   and Recreation.
SW 184th St. and 83rd Ave.......  Private...........  11-100 (1999) \1\.  Miami-Dade........  Insufficient data.
Castellow #33...................  Private...........  12 (1995) \3\.....  Miami-Dade........  Insufficient data.
Castellow #31...................  Private...........  30-50 (1995) \3\..  Miami-Dade........  Insufficient data.
----------------------------------------------------------------------------------------------------------------
                                              Extirpated 14 records
----------------------------------------------------------------------------------------------------------------
Upper Matecumbe Key.............  unknown...........  No estimate (1967)  Monroe............
                                                       \3\.
Totten Key......................  NPS...............  No estimate (1904)  Monroe............
                                                       \1\.
Key West........................  City of Key West..  No estimate (1965)  Monroe............
                                                       \1\.
Fuch's Hammock..................  Miami-Dade County.  No estimate (1991)  Miami-Dade........
                                                       \1\.
Brickell Hammock................  unknown...........  Extirpated 1937     Miami-Dade........
                                                       \1\.
Carribean Park..................  Miami-Dade County.  Extirpated 1998     Miami-Dade........
                                                       \1\.
Coconut Grove...................  Miami-Dade County.  Extirpated 1901     Miami-Dade........
                                                       \1\.
Coral Gables area...............  unknown...........  Extirpated 1967     Miami-Dade........
                                                       \1\.
Miller and 72nd Ave.............  unknown...........  Extirpated 1975     Miami-Dade........
                                                       \1\.
Orchid Jungle...................  Miami-Dade County.  Extirpated 1930     Miami-Dade........
                                                       \1\.
Palms Woodlawn Cemetery.........  Private...........  Extirpated 1992     Miami-Dade........
                                                       \1\.
South of Miami River............  unknown...........  Extirpated 1913     Miami-Dade........
                                                       \1\.
Bauer Drive Pineland............  Private...........  No estimate (1985)  Miami-Dade........
                                                       \3\.
Naranja.........................  Private...........  No estimate (1974)  Miami-Dade........
                                                       \3\.
----------------------------------------------------------------------------------------------------------------
\1\ Bradley and Gann 1999, p. 6.
\2\ Hodges and Bradley 2006, pp. 10-17.
\3\ FNAI 2011.
\4\ Sadle 2015, pers. comm., p. 1.
\5\ National Park Service (NPS).
\6\ Florida Department of Environmental Protection (FDEP).
\7\ Key West Naval Air Station (KWNAS).
\8\ Henize and Hipes 2005, p. 25.

Biology
    Life History and Reproduction: Reproductive biology of Argythamnia 
blodgettii has not been studied. Reproduction is sexual and flowering 
and fruiting apparently takes place throughout the year (Bradley and 
Gann 1999, p. 3).
    Fire Ecology and Demography: The fire ecology and demography of 
Argythamnia blodgettii have not been studied. Populations of A. 
blodgettii can be ephemeral (Hodges and Bradley 2006, p. 14).

Summary of Biological Status and Threats

    The Act directs us to determine whether any species is an 
endangered species or a threatened species because of any one of five 
factors affecting its continued existence. In this section, we 
summarize the biological condition of each of the plant species and its 
resources, and the factors affecting them, to assess the species' 
overall viability and the risks to that viability.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

    Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii have experienced 
substantial destruction, modification, and curtailment of their 
habitats and ranges (see Background, above). Specific threats to these 
plants included in this factor include habitat loss, fragmentation, and 
modification caused by development (i.e., conversion to both urban and 
agricultural land uses) and inadequate fire management. Each of these 
threats and its specific effects on these plants are discussed in 
detail below.
Human Population Growth, Development, and Agricultural Conversion
    The modification and destruction of the habitats that support 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii has been extreme 
in most areas of Miami-Dade and Monroe Counties, thereby reducing these 
plants' current ranges and abundance in Florida. The

[[Page 58550]]

pine rocklands community of south Florida, in which all four plants 
primarily occur, is critically imperiled locally and globally (FNAI 
2012, p. 27). Destruction of pine rocklands and rockland hammocks has 
occurred since the beginning of the 1900s. Extensive land clearing for 
human population growth, development, and agriculture in Miami-Dade and 
Monroe Counties has altered, degraded, or destroyed thousands of acres 
of these once abundant ecosystems.
    In Miami-Dade County, development and agriculture have reduced pine 
rocklands habitat by 90 percent in mainland south Florida. Pine 
rocklands habitat decreased from approximately 74,000 ha (183,000 ac) 
in the early 1900s, to only 8,140 ha (20,100 ac) in 1996 (Kernan and 
Bradley 1996, p. 2). The largest remaining intact pine rocklands 
(approximately 2,313 ha (5,716 ac)) is Long Pine Key in ENP. Outside of 
ENP, only about 1 percent of the pine rocklands on the Miami Rock Ridge 
have escaped clearing, and much of what is left are small remnants 
scattered throughout the Miami metropolitan area, isolated from other 
natural areas (Herndon 1998, p. 1).
    Similarly, most of the pine rocklands in the Florida Keys (Monroe 
County) have been impacted (Hodges and Bradley 2006, p. 6). Pine 
rocklands historically covered 1,049 ha (2,592 ac) of Big Pine Key 
(Folk 1991, p. 188), the largest area of pine rocklands in the Florida 
Keys. Pine rocklands now cover approximately 582 ha (1,438 ac) of the 
island, a reduction of 56 percent (Bradley and Saha 2009, p. 3). There 
were no estimates of pine rocklands area on the other islands 
historically, but each contained much smaller amounts of the habitat 
than Big Pine Key. Remaining pine rocklands on Cudjoe Key cover 72 ha 
(178 ac), Little Pine has 53 ha (131 ac), No Name has 56 ha (138 ac), 
and Sugarloaf has 38 ha (94 ac). The total area of remaining pine 
rocklands in the Florida Keys is approximately 801 ha (1,979 ac). 
Currently, about 478 ha (1,181 ac) (82 percent) of the pine rocklands 
on Big Pine Key, and most of the pine rocklands on these other islands, 
are protected within the National Key Deer Refuge and properties owned 
by the Nature Conservancy, the State of Florida, and Monroe County 
(Bradley and Saha 2009, pp. 3-4). Based on the data presented above, 
the total remaining acreage of pine rocklands in Miami-Dade and Monroe 
Counties is now 8,981 ha (22,079 ac) (approximately 8,140 ha (20,100 
ac) in Miami-Dade County, and 801 ha (1,979 ac) in the Florida Keys 
(Monroe County)).
    The marl prairies that also support Linum arenicola have similarly 
been destroyed by the rapid development of Miami-Dade and Monroe 
Counties. At least some of the occurrences reported from this habitat 
may be the result of colonization that occurred after they were 
artificially dried-out due to local or regional drainage.
    Likewise, habitat modification and destruction from residential and 
commercial development have severely impacted rockland hammocks, and 
coastal berm, that support Argythamnia blodgettii. Rockland hammocks 
were once abundant in Miami-Dade and Monroe Counties but are now 
considered imperiled locally and globally (FNAI 2010x, pp. 24-26). The 
tremendous development and agricultural pressures in south Florida have 
resulted in significant reductions of rockland hammock, which is also 
susceptible to fire, frost, hurricane damage, and groundwater reduction 
(Phillips 1940, p. 167; Snyder et al. 1990, pp. 271-272; FNAI 2010, pp. 
24-26).
    Pine rocklands, rockland hammock, marl prairie, and coastal 
habitats on private land remain vulnerable to development, which could 
lead to the loss of populations of these four species. As noted 
earlier, all four plants have been impacted by development. The sites 
of Small's 1907 and 1911 L. arenicola collections in Miami-Dade County 
are now agricultural fields (Kernan and Bradley 1996, p. 4). A pine 
rocklands site that supported L. arenicola on Vistalmar Street in Coral 
Gables (Miami-Dade County) was cleared and developed in 2005, as the 
Cocoplum housing development. A second pine rocklands site that 
supported L. arenicola, located on private land on Old Cutler Road, was 
developed into the Palmetto Bay Village Center. L. arenicola has not 
been observed at either site since they were developed. A former marl 
prairie site supporting a sizable population of L. arenicola near Old 
Cutler Road and Allapatah Drive (SW 112 Ave3.) in Miami-Dade County was 
extirpated when the site was developed in the 1990s (Bradley and van 
der Heiden 2013, pp. 6-12, 19). The Boca Chica Key population of L. 
arenicola was also likely lost due to development (Hodges and Bradley 
2006, p. 48).
    Bradley and Gann (1999, p. 6) list 12 populations of Argythamnia 
blodgettii in Miami-Dade County that were lost when the site that 
supported them was developed. An A. blodgettii population on Key West 
was likely lost due to the near complete urbanization of the island 
(Hodges and Bradley 2006, p. 43). Any development related to the Boy 
Scout camp on Big Munson Island is a potential threat to the largest 
population A. blodgettii.
    The largest Linum arenicola population in Miami-Dade County is 
located on property owned by the Miami-Dade County Homeless Trust. 
SOCSOUTH, a unified command of all four services of DOD, has entered 
into a 50-year agreement with Miami-Dade County to lease this 90-ac 
(36.4-ha) area, where they are building a permanent headquarters on 
approximately 28 ac (11.3 ha) (DOD 2009, p. 1). As stated above, the 
population of L. arenicola is spread across the site and was estimated 
at 74,000 plants in 2009 (Bradley 2009, p. 3). In consultation with the 
Service, the DOD developed a plan that avoided the majority of the 
population with accompanying protection and management of approximately 
57,725 individuals of sand flax (about 78 percent of the estimated 
onsite population) (Service 2011, p. 13). The plan will manage 5.95 ha 
(14.7 ac) of habitat, though most of it is scraped, and only a small 
portion has a pine canopy (Van der Heiden and Johnson 2013, p. 2). An 
additional 1.3 ha (3.2 ac) is being managed and supports 13,184 
individuals of sand flax (about 18 percent of the estimated onsite 
population) (Service 2011, p. 13).
    Currently there are plans to develop 55 ha (137 ac) of the largest 
remaining parcel of pine rocklands habitat in Miami-Dade County, the 
Richmond pine rocklands, with a shopping center and residential 
construction (RAM 2014, p. 2). Bradley and Gann (1999, p. 4) called the 
345-ha (853-ac) Richmond pine rocklands, ``the largest and most 
important area of pine rockland in Miami-Dade County outside of 
Everglades National Park.'' Populations of Argythamnia blodgettii and 
Linum arenicola, along with numerous federally listed species, occur 
there. The Miami-Dade County Department of Environmental Resources 
Management (DERM) has completed a management plan for portions of the 
Richmond pine rocklands under a grant from the Service and is leading 
the restoration and management of the Richmond pine rocklands (Bradley 
and Gann 1999, p. 4). The developer has proposed to enter into a 
habitat conservation plan in conjunction with their plans to develop 
their portion of the site and was required by Miami-Dade County Natural 
Forest Community (NFC) regulations to set aside and manage 15 ha (39 
ac) of pine rocklands and 2 ha (4 ac) of rockland hammock. A second 
project that would result in the loss of pine rocklands habitat is also 
planned for the

[[Page 58551]]

Richmond pine rocklands. It includes expanding the Miami Zoo complex to 
develop an amusement park and large retail mall.
    Approximately 25 percent of extant Linum arenicola occurrences (3 
of 12 sites), and 44 percent of extant Argythamnia blodgettii 
occurrences (13 of 34 sites), are located on private land; no extant 
populations of Chamaecrista lineata var. keyensis or Chamaesyce 
deltoidea ssp. serpyllum are located entirely on private land. It is 
possible that the plants on private lands will be lost from most of 
these sites in the future with increased pressure from development and 
the other threats described below. Argythamnia blodgettii is the only 
one of the four plants species which occurs in ENP, where a population 
of over 2,000 plants is stable and prescribed fire and other management 
activities that benefit A. blodgettii are conducted on a regular basis.
    Most pine rocklands and rockland hammock habitat is now limited to 
public conservation lands, where future development and habitat 
alteration are less likely than on private lands. However, public lands 
could be sold off (or leased) in the future and become more likely to 
be developed or altered in a way that negatively impacts the habitat. 
For example, at the SOCSOUTH site noted above (leased to DOD by Miami-
Dade County), ongoing development of headquarters buildings SOCSOUTH 
has resulted in the loss of L. arenicola and pine rocklands habitat 
(Bradley and van der Heiden 2013, pp. 8-10). Construction of visitor 
facilities such as parking lots, roads, trails, and buildings can 
result in habitat loss on public lands that are set aside as preserves 
or parks.
    Roadside populations of Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia 
blodgettii are vulnerable to habitat loss and modification stemming 
from infrastructure projects such as road widening, and installation of 
underground cable, sewer, and water lines. The Lower Sugarloaf Key 
population of Linum arenicola was impacted by repaving of the road, 
which placed asphalt on top of and adjacent to the population (Hodges 
and Bradley 2006, p. 41).
    Although no entire populations of Chamaecrista lineata var. 
keyensis or Chamaesyce deltoidea ssp. serpyllum have been extirpated by 
habitat loss due to development, the size and extent of these 
populations have been reduced on Big Pine Key (and surrounding islands 
for Chamecrista lineata var. keyensis). The total area of pine rockland 
on Big Pine Key has decreased by 56 percent from 1955 to the present 
(Bradley and Saha 2009, p. 3).
    The human population within Miami-Dade County is currently greater 
than 2.4 million people, and is expected to grow to more than 4 million 
by 2060, an annual increase of roughly 30,000 people (Zwick and Carr 
2006, p. 20). Overall, the human population in Monroe County is 
expected to increase from 79,589 to more than 92,287 people by 2060 
(Zwick and Carr 2006, p. 21). All vacant land in the Florida Keys is 
projected to be developed by then, including lands currently 
inaccessible for development, such as islands not attached to the 
Overseas Highway (U.S. 1) (Zwick and Carr 2006, p. 14). However, in an 
effort to address the impact of development on federally listed 
species, Monroe County implemented a habitat conservation plan (HCP) 
for Big Pine and No Name Keys in 2006. In order to fulfill the HCP's 
mitigation requirements, the County has been actively acquiring parcels 
of high-quality pine rocklands, such as The Nature Conservancy's 20-
acre Terrestris Tract on Big Pine Key, and managing them for 
conservation. Although the HCP has helped to limit the impact of 
development, land development pressure and habitat losses may resume 
when the HCP expires in 2023. If the HCP is not renewed, residential or 
commercial development could increase to pre-HCP levels.
    While Miami-Dade and Monroe County both have developed a network of 
public conservation lands that include pine rocklands, rockland 
hammocks, marl prairies, and coastal habitats, much of the remaining 
habitat occurs on private lands as well as publicly owned lands not 
managed for conservation. Species occurrences and suitable habitat 
remaining on these lands are threatened by habitat loss and 
degradation, and threats are expected to accelerate with increased 
development. Further losses will seriously affect the four plant 
species' ability to persist in the wild and decrease the possibility of 
their recovery or recolonization.
Habitat Fragmentation
    The remaining pine rocklands in the Miami metropolitan area are 
severely fragmented and isolated from each other by vast areas of 
development. Remaining pine rockland areas in the Florida Keys are 
fragmented and are located on small islands separated by ocean. Habitat 
fragmentation reduces the size of plant populations and increases 
spatial isolation of remnants. Barrios et al. (2011, p. 1062) 
investigated the effects of fragmentation on a pine rocklands plant, 
Angadenia berteroi (pineland golden trumpet), which is recognized by 
the State of Florida as threatened, and found that abundance and 
fragment size were positively related. Possley et al. (2008, p. 385) 
studied the effects of fragment size on species composition in south 
Florida pine rocklands, and found that plant species richness and 
fragment size were positively correlated (although some small fragments 
supported nearly as many species as the largest fragment). Composition 
of fragmented habitat typically differs from that of intact forests; as 
isolation and edge effects increase, there is increased abundance of 
disturbance-adapted species (weedy species, nonnative invasive species) 
and lower rates of pollination and propagule dispersal (Laurence and 
Bierregaard 1997, pp. 347-350; Noss and Csuti 1997, pp. 284-299). The 
degree to which fragmentation threatens the dispersal abilities of 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii is unknown. In 
the historical landscape, where pine rocklands occurred within a mosaic 
of wetlands, water may have acted as a dispersal vector for all pine 
rocklands seeds. In the current, fragmented landscape, this type of 
dispersal would no longer be possible for any of the Miami-Dade 
populations. While additional dispersal vectors may include animals and 
(in certain locations) mowing equipment, it is likely that 
fragmentation has effectively reduced these plants' ability to disperse 
and exchange genetic material.
    While pollination research has not been conducted for Chamaesyce 
deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia blodgettii, 
research regarding other species and ecosystems, including Chamaecrista 
lineata var. keyensis (discussed below), provides valuable information 
regarding potential effects of fragmentation on these plants. Effects 
of fragmentation on pollinators may include changes to the pollinator 
community as a result of limitation of pollinator-required resources 
(e.g., reduced availability of rendezvous plants, nesting and roosting 
sites, and nectar/pollen); these changes may include changes to 
pollinator community composition, species abundance and diversity, and 
pollinator behavior (Rathcke and Jules 1993, pp. 273-275; Kremen and 
Ricketts 2000, p. 1227; Harris and Johnson 2004, pp. 30-33). As a 
result, plants in fragmented habitats may experience lower visitation 
rates, which in turn may result in

[[Page 58552]]

reduced seed production of the pollinated plant (which may lead to 
reduced seedling recruitment), reduced pollen dispersal, increased 
inbreeding, reduced genetic variability, and ultimately reduced 
population viability (Rathcke and Jules 1993, p. 275; Goverde et al. 
2002, pp. 297-298; Harris and Johnson 2004, pp. 33-34).
    In addition to affecting pollination, fragmentation of natural 
habitats often alters other ecosystems' functions and disturbance 
regimes. Fragmentation results in an increased proportion of ``edge'' 
habitat, which in turn has a variety of effects, including changes in 
microclimate and community structure at various distances from the edge 
(Margules and Pressey 2000, p. 248), altered spatial distribution of 
fire (greater fire frequency in areas nearer the edge) (Cochrane 2001, 
pp. 1518-1519), and increased pressure from nonnative, invasive plants 
and animals that may out-compete or disturb native plant populations. 
Liu and Koptur (2003, p. 1184) reported decreases in Chamaecrista 
lineata var. keyensis's seed production in urban areas of Big Pine Key 
due to increased seed predation, compared with areas away from 
development.
    The effects of fragmentation on fire go beyond edge effects and 
include reduced likelihood and extent of fires, and altered behavior 
and characteristics (e.g., intensity) of those fires that do occur. 
Habitat fragmentation encourages the suppression of naturally occurring 
fires, and has prevented fire from moving across the landscape in a 
natural way, resulting in an increased amount of habitat suffering from 
these negative impacts. High fragmentation of small habitat patches 
within an urban matrix discourages the use of prescribed fire as well 
due to logistical difficulties (see ``Fire Management,'' below). Forest 
fragments in urban settings are also subject to increased likelihood of 
certain types of human-related disturbance, such as the dumping of 
trash (Chavez and Tynon 2000, p. 405). The many effects of habitat 
fragmentation may work in concert to threaten the local persistence of 
a species; when a species' range of occurrence is limited, threats to 
local persistence increase extinction risk.
Fire Management
    One of the primary threats to Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia 
blodgettii is habitat modification and degradation through inadequate 
fire management, which includes both the lack of prescribed fire and 
suppression of natural fires. Where the term ``fire-suppressed'' is 
used below, it describes degraded pine rocklands conditions resulting 
from a lack of adequate fire (natural or prescribed) in the landscape. 
Historically, frequent (approximately twice per decade), lightning-
induced fires were a vital component in maintaining native vegetation 
and ecosystem functioning within south Florida pine rocklands (see 
Background, above). A period of just 10 years without fire may result 
in a marked decrease in the number of herbaceous species due to the 
effects of shading and litter accumulation (FNAI 2010, p. 63). 
Exclusion of fire for approximately 25 years will likely result in 
gradual hammock development over that time period, leaving a system 
that is very fire-resistant if additional pre-fire management (e.g., 
mechanical hardwood removal) is not undertaken.
    Today, natural fires are unlikely to occur or are likely to be 
suppressed in the remaining, highly fragmented pine rocklands habitat. 
The suppression of natural fires has reduced the size of the areas that 
burn, and habitat fragmentation has prevented fire from moving across 
the landscape in a natural way. Without fire, successional climax from 
pine rocklands to rockland hammock is rapid, and displacement of native 
species by invasive, nonnative plants often occurs. Understory plants 
such as Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii are shaded out 
by hardwoods and nonnatives alike. Shading may also be caused by a 
fire-suppressed pine canopy that has evaded the natural thinning 
effects that fire has on seedlings and smaller trees. Whether the dense 
canopy is composed of pine, hardwoods, nonnatives, or a combination, 
seed germination and establishment are inhibited in fire-suppressed 
habitat due to accumulated leaf litter, which also changes soil 
moisture and nutrient availability (Hiers et al. 2007, pp. 811-812). 
This alteration to microhabitat can also inhibit seedling establishment 
as well as negatively influence flower and fruit production 
(Wendelberger and Maschinski 2009, pp. 849-851), thereby reducing 
sexual reproduction in fire-adapted species such as Chamaecrista 
lineata var. keyensis, Chamaesyce deltoidea ssp. serpyllum, L. 
arenicola, and A. blodgettii (Geiger 2002, pp. 78-79, 81-83).
    After an extended period of inadequate fire management in pine 
rocklands, it becomes necessary to control invading native hardwoods 
mechanically, as excess growth of native hardwoods would result in a 
hot fire, which can kill mature pines. Mechanical treatments cannot 
entirely replace fire because pine trees, understory shrubs, grasses, 
and herbs all contribute to an ever-increasing layer of leaf litter, 
covering herbs and preventing germination, as discussed above. Leaf 
litter will continue to accumulate even if hardwoods are removed 
mechanically. In addition, the ashes left by fires provide important 
post-fire nutrient cycling, which is not provided via mechanical 
removal.
    Federal (Service, NPS), State (FDEP, FWC), and County land managers 
(Miami-Dade DERM), and nonprofit organizations (IRC) implement 
prescribed fire on public and private lands within the ranges of these 
four plants. While management of some County conservation lands 
includes regular burning, other lands remain severely fire-suppressed. 
Even in areas under active management, some portions are typically 
fire-suppressed.
    Miami-Dade County: Implementation of a prescribed fire program in 
Miami-Dade County has been hampered by a shortage of resources, as well 
as by logistical difficulties and public concern related to burning 
next to residential areas. Many homes have been built in a mosaic of 
pine rocklands, so the use of prescribed fire in many places has become 
complicated because of potential danger to structures and smoke 
generated from the burns. Nonprofit organizations such as IRC have 
similar difficulties in conducting prescribed burns due to difficulties 
with permitting and obtaining the necessary permissions as well as 
hazard insurance limitations (Gann 2013a, pers. comm.). Few private 
landowners have the means or desire to implement prescribed fire on 
their property, and doing so in a fragmented urban environment is 
logistically difficult and may be costly.
    All occurrences of Linum arenicola and Argythamnia blodgettii in 
Miami-Dade County are affected by some degree of inadequate fire 
management of pine rocklands and marl prairie habitat, with the primary 
threat being the modification and loss of habitat due to an increase in 
shrub and hardwood dominance, eliminating suitable conditions for the 
four plants, and eventual succession to rockland hammock.
    In Miami-Dade County, Linum arenicola occurred along the south edge 
of Bauer Drive on the northern border of a pine rockland owned by 
Miami-Dade County. The property is occupied by a communications tower, 
and is not a managed preserve. Kernan and Bradley (1996) reported eight 
plants. At the time

[[Page 58553]]

(1992 through 1996), the road shoulder was dominated by native grasses. 
Since then, native canopy hardwoods have invaded the site and 
eliminated the sunny conditions required by L. arenicola. It has not 
been seen since, despite multiple surveys between 1997 and 2012, and is 
considered to be extirpated. L. arenicola was discovered at Camp 
Owaissa Bauer by George N. Avery in 1983. Since that time, the pine 
rocklands habitat where he found the plants in the park suffered 
extremely heavy hardwood recruitment due to fire suppression. Despite 
recent hardwood control and reintroduction of fire, no plants have been 
relocated. At the Martinez pineland, a population of L. arenicola in a 
marl prairie that became overgrown due to lack of fire has not been 
observed since 2011. Plants may reappear at this site if prescribed 
fire is implemented and viable seeds remain in the soil (Bradley and 
van der Heiden 2013, pp. 8-11). Bradley and Gann (1999, pp. 71-72) 
suggested that the lack of fires in most forest fragments in Miami-Dade 
County during the last century may be one of the reasons why L. 
arenicola occurs primarily in disturbed areas.
    Monroe County (Florida Keys): Fire management of pine rocklands of 
the lower Florida Keys, most of which are within NKDR, is hampered by a 
shortage of resources, technical challenges, and expense of conducting 
prescribed fire in a matrix of public and private ownership. 
Residential and commercial properties are embedded within or in close 
proximity to pine rocklands habitat (Snyder et al. 2005, p. 2; C. 
Anderson 2012a, pers. comm.). As a result, hand or mechanical 
vegetation management may be necessary at select locations on Big Pine 
Key (Emmel et al. 1995, p. 11; Minno 2009, pers. comm.; Service 2010, 
pp. 1-68) to maintain or restore pine rocklands. Mechanical treatments 
may be less beneficial than fire because they do not quickly convert 
debris to nutrients, and remaining leaf litter may suppress seedling 
development; fire has also been found to stimulate seedling germination 
(C. Anderson 2010, pers. comm.). Because mechanical treatments may not 
provide the same ecological benefits as fire, NKDR continues to focus 
efforts on conducting prescribed fire where possible (C. Anderson 
2012a, pers. comm.). However, the majority of pine rocklands within 
NKDR are several years behind the ideal fire return interval (5-7 
years) suggested for this ecosystem (Synder et al. 2005, p. 2; Bradley 
and Saha 2011, pp. 1-16). Tree ring and sediment data show that pine 
rocklands in the lower Keys have burned at least every 5 years and 
sometimes up to three times per decade historically (Albritton 2009, p. 
123; Horn et al. 2013, pp. 1-67; Harley 2012, pp. 1-246). From 1985 to 
1992, prescribed burns were conducted in the NKDR mainly for fuel 
reduction. There was no prescribed burning by Service staff in the NKDR 
from 1992-1997, in part because not enough was known about the 
ecological effects of prescribed fire in this system (Snyder et al. 
1990, p. 2).
    All occurrences of Chamaecrista lineata var. keyensis, Chamaesyce 
deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia blodgettii 
in the Florida Keys are affected by some degree of inadequate fire 
management of pine rocklands habitat, with the primary threat being the 
modification and loss of habitat due to an increase in shrub and 
hardwood dominance, eliminating suitable conditions for the four 
plants, and eventual succession to rockland hammock.
    Prescribed fire management over the past decade has not been 
sufficient to reverse long-term declines in Chamaecrista lineata var. 
keyensis, Chamaesyce deltoidea ssp. serpyllum, or Linum arenicola on 
Big Pine Key. Prescribed fire activity on Big Pine Key and adjacent 
islands within NKDR appears to be insufficient to prevent loss of pine 
rocklands habitat (Carlson et al. 1993, p. 914; Bergh and Wisby 1996, 
pp. 1-2; O'Brien 1998, p. 209; Bradley and Saha 2009, pp. 28-29; 
Bradley et al. 2011, pp. 1-16). As a result, many of the pine rocklands 
across NKDR are being compromised by succession to rockland hammock 
(Bradley and Saha 2009, pp. 28-29; Bradley et al. 2011, pp. 1-16).
Conservation Efforts To Reduce the Present or Threatened Destruction, 
Modification, or Curtailment of Habitat or Range
    Miami-Dade County Environmentally Endangered Lands (EEL) Covenant 
Program: In 1979, Miami-Dade County enacted the Environmentally 
Endangered Lands (EEL) Covenant Program, which reduces taxes for 
private landowners of natural forest communities (NFCs; pine rocklands 
and tropical hardwood hammocks) who agree not to develop their property 
and manage it for a period of 10 years, with the option to renew for 
additional 10-year periods (Service 1999, p. 3-177). Although these 
temporary conservation easements provide valuable protection for their 
duration, they are not considered under Factor D, below, because they 
are voluntary agreements and not regulatory in nature. Miami-Dade 
County currently has approximately 59 pine rocklands properties 
enrolled in this program, preserving 69.4 ha (172 ac) of pine rocklands 
habitat (Johnson 2012, pers. comm.). The program also has approximately 
21 rockland hammocks properties enrolled in this program, preserving 
20.64 ha (51 ac) of rockland hammock habitat (Joyner 2013b, pers. 
comm.). The vast majority of these properties are small, and many are 
in need of habitat management such as prescribed fire and removal of 
nonnative, invasive plants. Thus, while EEL covenant lands have the 
potential to provide valuable habitat for these plants and reduce 
threats in the near term, the actual effect of these conservation lands 
is largely determined by whether individual land owners follow 
prescribed EEL management plans and NFC regulations (see ``Local'' 
under Factor D discussion, below).
    Fee Title Properties: In 1990, Miami-Dade County voters approved a 
2-year property tax to fund the acquisition, protection, and 
maintenance of natural areas by the EEL Program. The EEL Program 
purchases and manages natural lands for preservation. Land uses deemed 
incompatible with the protection of the natural resources are 
prohibited by current regulations; however, the County Commission 
ultimately controls what may happen with any County property, and land 
use changes may occur over time (Gil 2013b, pers. comm.). To date, the 
Miami-Dade County EEL Program has acquired a total of approximately 313 
ha (775 ac) of pine rocklands, and 95 ha (236 ac) of rockland hammocks 
(Guerra 2015, pers. comm.; Gil 2013b, pers. comm.). The EEL Program 
also manages approximately 314 ha (777 ac) of pine rocklands, and 639 
ha (1,578 ac) of tropical hardwood and rockland hammocks owned by the 
Miami-Dade County Parks, Recreation and Open Spaces Department, 
including some of the largest remaining areas of pine rocklands habitat 
on the Miami Rock Ridge outside of ENP (e.g., Larry and Penny Thompson 
Park, Zoo Miami pinelands, Navy Wells Pineland Preserve), and some of 
the largest remaining areas of tropical hardwood and rockland hammocks 
(e.g., Matheson Hammock Park, Castellow Hammock Park, Deering Estate 
Park and Preserves).
    Conservation efforts in Miami's EEL Preserves have been underway 
for many years. In Miami-Dade County, conservation lands are and have 
been monitored by FTBG and IRC, in coordination with the EEL Program, 
to assess habitat status and determine any

[[Page 58554]]

changes that may pose a threat to or alter the abundance of these 
species. Impacts to habitat (e.g., canopy) via nonnative species and 
natural stochastic events are monitored and actively managed in areas 
where the taxon is known to occur. These programs are long-term and 
ongoing in Miami-Dade County; however, programs are limited by the 
availability of annual funding.
    Since 2005, the Service has funded IRC to facilitate restoration 
and management of privately owned pine rocklands habitats in Miami-Dade 
County. These programs included prescribed burns, nonnative plant 
control, light debris removal, hardwood management, reintroduction of 
pines where needed, and development of management plans. One of these 
programs, called the Pine Rockland Initiative, includes 10-year 
cooperative agreements between participating landowners and the 
Service/IRC to ensure restored areas will be managed appropriately 
during that time. Although most of these objectives have been achieved, 
IRC has not been able to conduct the desired prescribed burns, due to 
logistical difficulties as discussed earlier (see ``Fire Management,'' 
above).
    Connect to Protect Program: Fairchild Tropical Botanic Garden 
(FTBG), with the support of various Federal, State, and local agencies 
and nonprofit organizations, has established the ``Connect to Protect 
Network.'' The objective of this program is to encourage widespread 
participation of citizens to create corridors of healthy pine rocklands 
by planting stepping stone gardens and rights-of-way with native pine 
rocklands species, and restoring isolated pine rocklands fragments. By 
doing this, FTBG hopes to increase the probability that pollination and 
seed dispersal vectors can find and transport seeds and pollen across 
developed areas that separate pine rocklands fragments to improve gene 
flow between fragmented plant populations and increase the likelihood 
that these plants will persist over the long term. Although these 
projects may serve as valuable components toward the conservation of 
pine rocklands species and habitat, they are dependent on continual 
funding, as well as participation from private landowners, both of 
which may vary through time.
    National Wildlife Refuges: The National Wildlife Refuge System 
Improvement Act of 1997 (16 U.S.C. 668dd note) and the Fish and 
Wildlife Service Manual (601 FW 3, 602 FW 3) require maintaining 
biological integrity and diversity, require comprehensive conservation 
planning for each refuge, and set standards to ensure that all uses of 
refuges are compatible with their purposes and the Refuge System's 
wildlife conservation mission. The comprehensive conservation plans 
(CCP) address conservation of fish, wildlife, and plant resources and 
their related habitats, while providing opportunities for compatible 
wildlife-dependent recreation uses. An overriding consideration 
reflected in these plans is that fish and wildlife conservation has 
first priority in refuge management, and that public use be allowed and 
encouraged as long as it is compatible with, or does not detract from, 
the Refuge System mission and refuge purpose(s). The CCP for the Lower 
Florida Keys National Wildlife Refuges (NKDR, Key West National 
Wildlife Refuge, and Great White Heron National Wildlife Refuge) 
provides a description of the environment and priority resource issues 
that were considered in developing the objectives and strategies that 
guide management over the next 15 years. The CCP promotes the 
enhancement of wildlife populations by maintaining and enhancing a 
diversity and abundance of habitats for native plants and animals, 
especially imperiled species that are found only in the Florida Keys. 
The CCP also provides for obtaining baseline data and monitoring 
indicator species to detect changes in ecosystem diversity and 
integrity related to climate change. The CCP provides specifically for 
maintaining and expanding populations of candidate plant species, 
including Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii, all four of 
which are found in this refuge complex.
    Department of Defense Lands: The Sikes Act requires the DOD to 
develop and implement integrated natural resources management plans 
(INRMPs) for military installations across the United States (see also 
Factor D discussion, below). INRMPs are prepared in cooperation with 
the Service and State fish and wildlife agencies to ensure proper 
consideration of fish, wildlife, and habitat needs. The DOD has an 
approved INRMP for KWNAS on Boca Chica Key that includes measures that 
will protect and enhance Argythamnia blodgettii habitat, including 
nonnative species control (DOD 2014, p. 69). Furthermore, DOD is 
currently preparing an INRMP for HARB and SOCSOUTH. A previous 
biological opinion (Service 2011, entire) required SOCSOUTH to protect 
and manage 7.4 ha (18.3 ac) of pine rocklands habitat and 70,909 
individuals of Linum arenicola (approximately 96 percent of the 
estimated onsite population) based on 2009 survey data. A conservation 
easement was established over the protected areas, and DOD has provided 
funds for management of the site, including fencing and nonnative 
species control.
Summary of Factor A
    We have identified a number of threats to the habitat of 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii that have 
operated in the past, are impacting these species now, and will 
continue to impact them in the future. Habitat loss, fragmentation, and 
degradation, and associated pressures from increased human population, 
are major threats; these threats are expected to continue, placing 
these plants at greater risk. All four plants may be impacted when pine 
rocklands are converted to other uses or when lack of fire causes the 
conversion to hardwood hammocks or other unsuitable habitat conditions. 
Any populations of these species found on private property could be 
destroyed by development; the limited pine rocklands, rockland hammock, 
and coastal berm habitat on public lands can also be affected by 
development of recreational facilities or infrastructure projects. 
Although efforts are being made to conserve publicly and privately 
owned natural areas and apply prescribed fire, the long-term effects of 
large-scale and wide-ranging habitat modification, destruction, and 
curtailment will last into the future, while ongoing habitat loss due 
to population growth, development, and agricultural conversion 
continues to pose a threat. Therefore, based on the best information 
available, we have determined that the threats to the four plants from 
habitat destruction, modification, or curtailment are occurring 
throughout the entire range of the species and are expected to continue 
into the future.

Factor B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    The best available data do not indicate that overutilization for 
commercial, recreational, scientific, or educational purposes is a 
threat to Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, or Argythamnia blodgettii. Threats to these 
plants related to other aspects of recreation and similar human 
activities (i.e., not related to overutilization) are discussed under 
Factor E.

[[Page 58555]]

Factor C. Disease or Predation

    No diseases or incidences of predation have been reported for 
Chamaesyce deltoidea ssp. serpyllum or Argythamnia blodgettii.
    Key deer are known to occasional browse plants indiscriminately, 
including Chamaecrista lineata var. keyensis and Linum arenicola. Key 
deer do not appear to feed on Argythamnia blodgettii, probably due to 
potential toxicity (Hodges and Bradley 2006, p. 19).
    Seed predation by an insect occurs in Chamaecrista lineata var. 
keyensis, and seems to be exacerbated by habitat fragmentation. 
Individuals at the urban edge suffer higher insect seed predation than 
those inside the forest (Liu and Koptur 2003, p. 1184).
    While seed predation and occasional Key deer browsing may be a 
stressor, they do not appear to rise to the level of threat at this 
time. Therefore, the best available data do not indicate that disease 
or predation is a threat to Chamaecrista lineata var. keyensis or Linum 
arenicola.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

    Under this factor, we examine whether threats to these plants are 
discussed under the other factors are continuing due to an inadequacy 
of an existing regulatory mechanism. Section 4(b)(1)(A) of the Act 
requires the Service to take into account ``those efforts, if any, 
being made by any State or foreign nation, or any political subdivision 
of a State or foreign nation, to protect such species.'' In relation to 
Factor D under the Act, we interpret this language to require the 
Service to consider relevant Federal, State, and tribal laws, 
regulations, and other such mechanisms that may minimize any of the 
threats we describe in threat analyses under the other four factors, or 
otherwise enhance conservation of the species. We give strongest weight 
to statutes and their implementing regulations and to management 
direction that stems from those laws and regulations. An example would 
be State governmental actions enforced under a State statute or 
constitution or Federal action under statute.
    Having evaluated the impact of the threats as mitigated by any such 
conservation efforts, we analyze under Factor D the extent to which 
existing regulatory mechanisms are inadequate to address the specific 
threats to the species. Regulatory mechanisms, if they exist, may 
reduce or eliminate the impacts from one or more identified threats. In 
this section, we review existing Federal, State, and local regulatory 
mechanisms to determine whether they effectively reduce or remove 
threats to Chamaecrista lineata var. keyensis, Chamaesyce deltoidea 
ssp. serpyllum, Linum arenicola, and Argythamnia blodgettii.
Federal
    As Federal candidate species, the four plant species are afforded 
some protection through sections 7 and 10 of the Act and associated 
policies and guidelines. Service policy requires candidate species be 
treated as proposed species for purposes of intra-Service consultations 
and conferences where the Service's actions may affect candidate 
species. Other Federal action agencies (e.g., NPS) are to consider the 
potential effects (e.g., prescribed fire, pesticide treatments) to 
these plants and their habitat during the consultation and conference 
process. Applicants and Federal action agencies are encouraged to 
consider candidate species when seeking incidental take for other 
listed species and when developing habitat conservation plans. However, 
candidate species do not receive the same level of protection that a 
listed species would under the Act.
    Populations of Argythamnia blodgettii within ENP are protected by 
NPS regulations at 36 CFR 2.1, which prohibit visitors from harming or 
removing plants, listed or otherwise, from ENP. However, the 
regulations do not address actions taken by NPS that cause habitat loss 
or modification.
    Populations of the four plants within Florida Keys Wildlife Refuge 
Complex benefit from the National Wildlife Refuge System Improvement 
Act of 1997 and the Fish and Wildlife Service Manual (601 FW 3, 602 FW 
3), which require the Service to maintain biological integrity and 
diversity, require comprehensive conservation planning for each refuge, 
and set standards to ensure that all uses of refuges are compatible 
with their purposes and the Refuge System's wildlife conservation 
mission. The CCP for a refuge addresses conservation of fish, wildlife, 
and plant resources and their related habitats, while providing 
opportunities for compatible wildlife-dependent recreation uses. An 
overriding consideration reflected in these plans is that fish and 
wildlife conservation has first priority in refuge management, and that 
public use be allowed and encouraged as long as it is compatible with, 
or does not detract from, the Refuge System mission and refuge 
purpose(s).
    The CCP for the Lower Florida Keys National Wildlife Refuges 
(National Key Deer Refuge, Key West National Wildlife Refuge, and Great 
White Heron National Wildlife Refuge) and the CCP for the Crocodile 
Lake National Wildlife Refuge provide for Chamaecrista lineata var. 
keyensis, Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and 
Argythamnia blodgettii as described above. Linum arenicola occurs on 
DOD lands at HARB and SOCSOUTH. L. arenicola and A. blodgettii occur on 
Federal lands within the Richmond Pinelands Complex, including lands 
owned by the U.S. Coast Guard and the National Oceanic and Atmospheric 
Association (NOAA; small portion of Martinez Pineland).
    As discussed under Factor A, above, the DOD has an approved INRMP 
for KWNAS on Boca Chica Key that includes measures that will protect 
and enhance Argythamnia blodgettii habitat, including nonnative species 
control (DOD 2014, p. 69). Furthermore, DOD is currently preparing an 
INRMP for HARB and SOCSOUTH. A 2011 Service biological opinion requires 
SOCSOUTH to protect and manage 7.4 ha (18.3 ac) of pine rocklands 
habitat and 70,909 individuals of Linum arenicola (approximately 96 
percent of the estimated onsite population) based on 2009 survey data. 
A conservation easement was established over the protected areas, and 
DOD has provided funds for management of the site, including fencing 
and nonnative species control.
    Populations of the four plants that occur on State- or County-owned 
properties and development of these areas will likely require no 
Federal permit or other authorization. Therefore, projects that affect 
them on State- and County-owned lands do not have Federal oversight, 
such as complying with the National Environmental Policy Act (NEPA) (42 
U.S.C. 4321 et seq.), unless the project has a Federal nexus (Federal 
funding, permits, or other authorizations). Therefore, the four plants 
have no direct Federal regulatory protection in these areas.
State
    Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii are listed on 
the Regulated Plant Index (Index) as endangered under chapter 5B-40, 
Florida Administrative Code. This listing provides little or no habitat 
protection beyond the State's development of a regional impact process, 
which discloses impacts from projects, but provides no regulatory 
protection for State-listed plants on private lands.

[[Page 58556]]

    Florida Statutes 581.185 sections (3)(a) and (3)(b) prohibit any 
person from willfully destroying or harvesting any species listed as 
endangered or threatened on the Index, or growing such a plant on the 
private land of another, or on any public land, without first obtaining 
the written permission of the landowner and a permit from the Florida 
Department of Plant Industry. The statute further provides that any 
person willfully destroying or harvesting; transporting, carrying, or 
conveying on any public road or highway; or selling or offering for 
sale any plant listed in the Index as endangered must have a permit 
from the State at all times when engaged in any such activities. 
Further, Florida Statutes 581.185 section (10) provides for 
consultation similar to section 7 of the Act for listed species, by 
requiring the Department of Transportation to notify the FDACS and the 
Endangered Plant Advisory Council of planned highway construction at 
the time bids are first advertised, to facilitate evaluation of the 
project for listed plant populations, and to provide ``for the 
appropriate disposal of such plants'' (i.e., transplanting).
    However, this statute provides no substantive protection of habitat 
or protection of potentially suitable habitat at this time. Florida 
Statutes 581.185 section (8) waives State regulation for certain 
classes of activities for all species on the Index, including the 
clearing or removal of regulated plants for agricultural, forestry, 
mining, construction (residential, commercial, or infrastructure), and 
fire-control activities by a private landowner or his or her agent.
Local
    In 1984, section 24-49 of the Code of Miami-Dade County established 
regulation of County-designated NFCs. These regulations were placed on 
specific properties throughout the County by an act of the Board of 
County Commissioners in an effort to protect environmentally sensitive 
forest lands. The Miami-Dade County Department of Regulatory and 
Economic Resources (RER) has regulatory authority over these County-
designated NFCs and is charged with enforcing regulations that provide 
partial protection of remaining upland forested areas designated as NFC 
on the Miami Rock Ridge. NFC regulations are designed to prevent 
clearing or destruction of native vegetation within preserved areas. 
Miami-Dade County Code typically allows up to 20 percent of pine 
rocklands designated as NFC to be developed, and requires that the 
remaining 80 percent be placed under a perpetual covenant. The code 
requires that no more than 10 percent of a rockland hammock designated 
as NFC may be developed for properties greater than 5 acres and that 
the remaining 90 percent be placed under a perpetual covenant for 
preservation purposes (Joyner 2013a, 2014, pers. comm.; Lima 2014, 
pers. comm.). However, for properties less than 5 acres, up to one-half 
an acre may be cleared if the request is deemed a reasonable use of 
property; this allowance often may be greater than 20 percent (for pine 
rocklands) or 10 percent (for rockland hammock) of the property (Lima 
2014, pers. comm.). NFC landowners are also required to obtain an NFC 
permit for any work, including removal of nonnatives within the 
boundaries of the NFC on their property. When RER discovers unpermitted 
work, it takes appropriate enforcement action and seeks restoration 
when possible. The NFC program is responsible for ensuring that NFC 
permits are issued in accordance with the limitations and requirements 
of the county code and that appropriate NFC preserves are established 
and maintained in conjunction with the issuance of an NFC permit when 
development occurs. The NFC program currently regulates approximately 
600 pine rocklands or pine rocklands/hammock properties, comprising 
approximately 1,200 ha (3,000 ac) of habitat (Joyner 2013, pers. 
comm.).
    Although the NFC program is designed to protect rare and important 
upland (non-wetlands) habitats in south Florida, it is a regulatory 
strategy with limitations. For example, in certain circumstances where 
landowners can demonstrate that limiting development to 20 percent (for 
pine rocklands) or 10 percent (for rockland hammock) does not allow for 
``reasonable use'' of the property, additional development may be 
approved. Furthermore, Miami-Dade County Code provides for up to 100 
percent of the NFC to be developed in limited circumstances for parcels 
less than 2.02 ha (5 ac) in size and only requires coordination with 
landowners if they plan to develop property or perform work within the 
NFC designated area. Therefore, many of the existing private forested 
NFC parcels remain fragmented, without management obligations or 
preserve designation, as development has not been proposed at a level 
that would trigger the NFC regulatory requirements. Often, nonnative 
vegetation over time begins to dominate and degrade the undeveloped and 
unmanaged NFC landscape until it no longer meets the legal threshold of 
an NFC, which applies only to land dominated by native vegetation. When 
development of such degraded NFCs is proposed, Miami-Dade County Code 
requires delisting of the degraded areas as part of the development 
process. Property previously designated as NFC is removed from the list 
even before development is initiated because of the abundance of 
nonnative species, making it no longer considered to be jurisdictional 
or subject to the NFC protection requirements of Miami-Dade County Code 
(Grossenbacher 2013, pers. comm.).
Summary of Factor D
    Currently, Chamaecrista lineata var. keyensis, Chamaesyce deltoidea 
ssp. serpyllum, Linum arenicola, and Argythamnia blodgettii are found 
on Federal, State, and County lands; however, there is no regulatory 
mechanism in place that provides substantive protection of habitat or 
protection of potentially suitable habitat at this time. NPS and USFWS 
Refuge regulations provide protection at ENP and the Florida Keys 
Wildife Refuge Complex, respectively. The Act provides some protection 
for candidate species on NWRs and during intra-Service section 7 
consultations. State regulations provide protection against trade, but 
allow private landowners or their agents to clear or remove species on 
the Florida Regulated Plant Index. State Park regulations provide 
protection for plants within Florida State Parks. The NFC program in 
Miami is designed to protect rare and important upland (non-wetlands) 
habitats in south Florida; however, this regulatory strategy has 
several limitations (as described above) that reduce its ability to 
protect the four plants and their habitats.
    Although many populations of the four plants are afforded some 
level of protection because they are on public conservation lands, 
existing regulatory mechanisms have not led to a reduction or removal 
of threats posed to these plants by a wide array of sources (see 
discussions under Factor A, above, and Factor E, below).

Factor E. Other Natural or Manmade Factors Affecting Its Continued 
Existence

    Other natural or manmade factors affect Chamaecrista lineata var. 
keyensis, Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and 
Argythamnia blodgettii to varying degrees. Specific threats to these 
plants included in this factor consist of the spread of nonnative, 
invasive plants;

[[Page 58557]]

potentially incompatible management practices (such as mowing and 
herbicide use); direct impacts to plants from recreation and other 
human activities; small population size and isolation; effects of 
pesticide spraying on pollinators; climate change and sea level rise 
(SLR); and risks from environmental stochasticity (extreme weather) on 
these small populations. Each of these threats and its specific effect 
on these plants is discussed in detail below.
Nonnative Plant Species
    Nonnative, invasive plants compete with native plants for space, 
light, water, and nutrients, and make habitat conditions unsuitable for 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii, which prefer 
open conditions. Bradley and Gann (1999, pp. 13, 71-72) indicated that 
the control of nonnative plants is one of the most important 
conservation actions for these plants and a critical part of habitat 
maintenance.
    Nonnative plants have significantly affected pine rocklands, and 
threaten all occurrences of these four species to some degree (Bradley 
2006, pp. 25-26; Bradley and Gann 1999, pp. 18-19; Bradley and Saha 
2009, p. 25; Bradley and van der Heiden 2013, pp. 12-16). As a result 
of human activities, at least 277 taxa of nonnative plants have invaded 
pine rocklands throughout south Florida (Service 1999, p. 3-175). 
Neyraudia neyraudia (Burma reed) and Schinus terebinthifolius 
(Brazilian pepper) threaten all four species (Bradley and Gann 1999, 
pp. 13, 72). S. terebinthifolius, a nonnative tree, is the most 
widespread and one of the most invasive species. It forms dense 
thickets of tangled, woody stems that completely shade out and displace 
native vegetation (Loflin 1991, p. 19; Langeland and Craddock Burks 
1998, p. 54). Acacia auriculiformis (earleaf acacia), Rhynchelytrum 
repens (natal grass), Lantana camara (shrub verbena), and Albizia 
lebbeck (tongue tree) are some of the other nonnative species in pine 
rocklands. More species of nonnative plants could become problems in 
the future, such as Lygodium microphyllum (Old World climbing fern), 
which is a serious threat throughout south Florida. Nonnative plants in 
pine rocklands can also affect the characteristics of a fire when it 
does occur. Historically, pine rocklands had an open, low understory 
where natural fires remained patchy with low temperature intensity, 
thus sparing many native plants such as Chamaecrista lineata var. 
keyensis, Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and 
Argythamnia blodgettii. Dense infestations of Neyraudia neyraudia and 
Schinus terebinthifolius cause higher fire temperatures and longer 
burning periods. With the presence of invasive, nonnative species, it 
is uncertain how fire, even under a managed situation, will affect 
these plants.
    At least 162 nonnative plant species are known to invade rockland 
hammocks; impacts are particularly severe on the Miami Rock Ridge 
(Service 1999, pp. 3-135). Nonnative plant species have significantly 
affected rockland hammocks where Argythamnia blodgettii occurs and are 
considered one of the threats to the species (Snyder et al. 1990, p. 
273; Hodges and Bradley 2006, p. 14). In many Miami-Dade County parks, 
nonnative plant species comprise 50 percent of the flora in hammock 
fragments (Service 1999, pp. 3-135). Horvitz (et al. 1998, p. 968) 
suggests the displacement of native species by nonnative species in 
conservation and preserve areas is a complex problem with serious 
impacts to biodiversity conservation, as management in these areas 
generally does not protect native species and ecological processes, as 
intended. Problematic nonnative, invasive plants associated with 
rockland hammocks include Leucaena leucocephala (lead tree), Schinus 
terebinthifolius, Bischofia javanica (bishop wood), Syngonium 
podophyllum (American evergreen), Jasminum fluminense (Brazilian 
jasmine), Rubus niveus (mysore raspberry), Thelypteris opulenta 
(jeweled maiden fern), Nephrolepis multiflora (Asian swordfern), 
Schefflera actinophylla (octopus tree), Jasminum dichotomum (Gold Coast 
jasmine), Epipremnum pinnatum (centipede tongavine), and Nephrolepis 
cordifolia (narrow swordfern) (Possley 2013h-i, pers. comm.).
    Management of nonnative, invasive plants in pine rocklands and 
rockland hammocks in Miami-Dade County is further complicated because 
the vast majority of pine rocklands and rockland hammocks are small, 
fragmented areas bordered by urban development. In the Florida Keys, 
larger fragments are interspersed with development. Developed or 
unmanaged areas that contain nonnative species can act as a seed source 
for nonnatives, allowing them to continue to invade managed pine 
rocklands or rockland hammocks (Bradley and Gann 1999, p. 13).
    Nonnative plant species are also a concern on private lands, where 
often these species are not controlled due to associated costs, lack of 
interest, or lack of knowledge of detrimental impacts to the ecosystem. 
Undiscovered populations of the four plants on private lands could 
certainly be at risk. Overall, active management is necessary to 
control for nonnative species and to protect unique and rare habitats 
where the four plants occur (Snyder et al. 1990, p. 273).
Management of Roadsides and Disturbed Areas
    All four plants occur in disturbed areas such as roadsides and 
areas that formerly were pine rocklands. Linum arenicola is 
particularly vulnerable to management practices in these areas because 
nearly all populations of the species are currently found on disturbed 
sites. The large L. arenicola population at HARB and SOCSOUTH is 
located largely in areas that are regularly mowed. Similarly, the small 
population of L. arenicola at the Everglades Archery Range, which is 
owned by Miami-Dade County and managed as a part of Camp Owaissa Bauer, 
is growing along the edges of the unimproved perimeter road that is 
regularly mowed. Finally, the two populations of L. arenicola on canal 
banks are subject to mowing, herbicide treatments, and revegetation 
efforts (sodding) (Bradley and van der Heiden 2013, pp. 8-10). The 
population of Argythamnia blodgettii at Lignumvitae Key Botanical State 
Park grows around the perimeter of the large lawn around the residence. 
Maintenance activities and encroachment of exotic lawn grasses are 
potential threats to this population (Hodges and Bradley 2006, p. 14). 
At Windley Key State Park, A. blodgettii grows in two quarry bottoms. 
In the first, larger quarry, to the east of the visitor center, plants 
apparently persist only in natural areas not being mowed. However, the 
majority of the plants are in the farthest quarry, which is not mowed 
(Hodges and Bradley 2006, p. 15).
    While no studies have investigated the effect of mowing on the four 
plants, research has been conducted on the federally endangered Linum 
carteri var. carteri (Carter's small-flowered flax, a close relative of 
Linum arenicola that also occurs in pine rocklands and disturbed 
sites). The study found significantly higher densities of plants at the 
mown sites where competition with other plants is decreased (Maschinski 
and Walters 2007, p. 56). However, plants growing on mown sites were 
shorter, which may affect fruiting magnitude. While mowing did not 
usually kill adult plants, if mowing occurred prior to plants reaching 
reproductive status, it could delay

[[Page 58558]]

reproduction (Maschinski and Walters 2007, pp. 56-57). If such mowing 
occurs repeatedly, reproduction of those plants would be entirely 
eliminated. If, instead, mowing occurs at least 3 weeks after 
flowering, there would be a higher probability of adults setting fruit 
prior to mowing; mowing may then act as a positive disturbance by both 
scattering seeds and reducing competition (Maschinski and Walters 2007, 
p. 57). The exact impacts of mowing thus depend on the timing of the 
mowing event, rainfall prior to and following mowing, and the numbers 
of plants in the population that have reached a reproductive state.
    Herbicide applications, the installation of sod, and dumping may 
affect populations of the four plants that occur on roadsides, canals 
banks, and other disturbed sites. Signs of herbicide application were 
noted at the site of the Big Torch Key roadside population of Linum 
arenicola in 2010 (Hodges 2010, p. 2). At the L-31 E canal site, plants 
of L. arenicola were lost on the levee close to Card Sound Road due to 
the installation of Bahia grass (Paspalum conjugatum) sod in recent 
years, an activity associated with the installation of new culverts. If 
similar projects are planned, other erosion control measures should be 
investigated that do not pose a threat to L. arenicola (Bradley and Van 
Der Heiden 2013, p. 10). Illegal dumping of storm-generated trash after 
Hurricane Wilma had a large impact on roadside populations of plants in 
the lower Florida Keys (Hodges and Bradley 2006, pp. 11-12, 19, 39).
    All populations of the four plants that occur on disturbed sites 
are vulnerable to regular maintenance activities such as mowing and 
herbicide applications, and dumping. This includes portions of all 
populations of Chamaecrista lineata var. keyensis and Chamaesyce 
deltoidea ssp. serpyllum, 10 of 12 Linum arenicola populations, and 5 
of 34 Argythamnia blodgettii populations. All roadside populations are 
also vulnerable to infrastructure projects such as road widening and 
installation of underground cable, sewer, and water lines.
Pesticide Effects on Pollinators
    Another possible anthropogenic threat to the four plants is current 
application of insecticides throughout these plants' ranges to control 
mosquito populations. Currently, an aerial insecticide (1,2-dibromo-
2,2-dichloroethyl dimethyl phosphate) and ground insecticide 
(Permethrin) are applied sometimes as frequently as daily in May 
through November in many parts of south Florida. Nontarget effects of 
mosquito control may include the loss of pollinating insects upon which 
certain plants depend.
    Koptur and Liu (2003, p. 1184) reported a decrease in Chamaecrista 
lineata var. keyensis pollinator activity following mosquito spraying 
on Big Pine Key. Mosquito spraying is common on Big Pine Key, and its 
suppression of pollinator populations may have a long-term impact on 
reproduction rates. Similar problems with mosquito spraying and effects 
of forest fragmentation and proximity to homes and business may also be 
impacting Chamaesyce deltoidea ssp. serpyllum and Linum arenicola 
(Bradley 2006, p. 36).
Environmental Stochasticity
    Endemic species whose populations exhibit a high degree of 
isolation and narrow geographic distribution, such as Chamaecrista 
lineata var. keyensis, Chamaesyce deltoidea ssp. serpyllum, Linum 
arenicola, and Argythamnia blodgettii, are extremely susceptible to 
extinction from both random and nonrandom catastrophic natural or 
human-caused events. Of the four species, Argythamnia blodgettii is 
probably less vulnerable because of the larger number of sites where it 
occurs throughout Miami-Dade and Monroe Counties. Small populations of 
species, without positive growth rates, are considered to have a high 
extinction risk from site-specific demographic and environmental 
stochasticity (Lande 1993, pp. 911-927).
    The climate of south Florida is driven by a combination of local, 
regional, and global weather events and oscillations. There are three 
main ``seasons'': (1) The wet season, which is hot, rainy, and humid 
from June through October; (2) the official hurricane season that 
extends one month beyond the wet season (June 1 through November 30), 
with peak season being August and September; and (3) the dry season, 
which is drier and cooler, from November through May. In the dry 
season, periodic surges of cool and dry continental air masses 
influence the weather with short-duration rain events followed by long 
periods of dry weather.
    Florida is considered the most vulnerable State in the United 
States to hurricanes and tropical storms (Florida Climate Center, 
https://coaps.fsu.edu/climate_center). Based on data gathered from 1856 
to 2008, Klotzbach and Gray (2009, p. 28) calculated the climatological 
probabilities for each State being impacted by a hurricane or major 
hurricane in all years over the 152-year timespan. Of the coastal 
States analyzed, Florida had the highest climatological probabilities, 
with a 51 percent probability of a hurricane (Category 1 or 2) and a 21 
percent probability of a major hurricane (Category 3 or higher). From 
1856 to 2008, Florida experienced 109 hurricanes, 36 of which were 
considered major hurricanes. Given the few isolated populations and 
restricted range of the four plants in locations prone to storm 
influences (i.e., Miami-Dade and Monroe Counties), they are at 
substantial risk from hurricanes, storm surges, and other extreme 
weather events.
    Hurricanes, storm surge, and extreme high tide events are natural 
events that can pose a threat to the four plants. Hurricanes and 
tropical storms can modify habitat (e.g., through storm surge) and have 
the potential to destroy entire populations. Climate change may lead to 
increased frequency and duration of severe storms (Golladay et al. 
2004, p. 504; McLaughlin et al. 2002, p. 6074; Cook et al. 2004, p. 
1015). The four plants experienced these disturbances historically, but 
had the benefit of more abundant and contiguous habitat to buffer them 
from extirpations. With most of the historical habitat having been 
destroyed or modified, the few remaining populations of these plants 
could face local extirpations due to stochastic events.
    The Florida Keys were impacted by three hurricanes in 2005: Katrina 
on August 26, Rita on September 20, and Wilma on October 24. Hurricane 
Wilma had the largest impact, with storm surges flooding much of the 
landmass of the Keys. In some places this water impounded and sat for 
days. The vegetation in many areas was top-killed due to salt water 
inundation (Hodges and Bradley 2006, p. 9). Flooding kills plants that 
do not have adaptations to tolerate anoxic soil conditions that persist 
after flooding; the flooding and resulting high salinities might also 
impact soil seed banks of the four plants (Bradley and Saha 2009, pp. 
27-28). After hurricane Wilma, the herb layer in pine rocklands in 
close proximity to the coast was brown with few plants having live 
material above ground (Bradley 2006, p. 11). Subsequent surveys found 
no Linum arenicola and little Chamaecrista lineata var. keyensis or 
Chamaesyce deltoidea ssp. serpyllum in areas where they previously 
occurred. Not only did the storm surge kill the vegetation, but many of 
the roadside areas were heavily disturbed by dumping and removal of 
storm debris (Bradley 2006, p. 37). Estimates of the population sizes 
pre- and post-Wilma were calculated for Chamaesyce

[[Page 58559]]

deltoidea ssp. serpyllum and Chamaecrista lineata var. keyensis. Each 
declined in the months following the storm, by 41.2 percent and 48.0 
percent, respectively (Bradley and Saha 2009, p. 2). L. arenicola was 
not found at all in surveys 8 to 9 weeks after the hurricane (Bradley 
2006, p. 36). The Middle Torch Key population was extirpated after 
Hurricane Wilma, and the population on Big Torch Key declined 
drastically, with only one individual located. Both of these areas were 
heavily affected by storm surges during Hurricane Wilma (Hodges 2010, 
p. 2). As of 2013, populations of Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, and L. arenicola in the Florida 
Keys have not returned to pre-Hurricane Wilma levels (Bradley et al. 
2015, pp. 21, 25, 29).
    Some climate change models predict increased frequency and duration 
of severe storms, including hurricanes and tropical storms (McLaughlin 
et al. 2002, p. 6074; Cook et al. 2004, p. 1015; Golladay et al. 2004, 
p. 504). Other models predict hurricane and tropical storm frequencies 
in the Atlantic are expected to decrease between 10 and 30 percent by 
2100 (Knutson et al. 2008, pp. 1-21). For those models that predict 
fewer hurricanes, predictions of hurricane wind speeds are expected to 
increase by 5 to 10 percent due to an increase in available energy for 
intense storms. Increases in hurricane winds can elevate the chances of 
damage to existing canopy and increase storm surge heights.
    All populations of the four plants are vulnerable to hurricane wind 
damage. Populations close to the coast and all populations of the four 
plants in the Florida Keys are vulnerable to inundation by storm surge. 
Historically, the four plant species may have benefitted from more 
abundant and contiguous habitat to buffer them from storm events. The 
small size of many populations of these plants makes them especially 
vulnerable, in which the loss of even a few individuals could reduce 
the viability of a single population. The destruction and modification 
of native habitat, combined with small population size, has likely 
contributed over time to the stress, decline, and, in some instances, 
extirpation of populations or local occurrences due to stochastic 
events.
    Due to the small size of some existing populations of Chamaecrista 
lineata var. keyensis, Linum arenicola, and Argythamnia blodgettii (see 
below) and the narrow geographic range of all four plant species, their 
overall resilience to these factors is likely low. These factors, 
combined with additional stress from habitat loss and modification 
(e.g., inadequate fire management) may increase the inherent risk of 
stochastic events that impact these plants. For these reasons, all four 
plants are at risk of extirpation during extreme stochastic events. Of 
the four species, Argythamnia blodgettii is probably less vulnerable 
because of the larger number of sites where it occurs throughout Miami-
Dade and Monroe Counties.
Small Population Size and Isolation
    Endemic species whose populations exhibit a high degree of 
isolation are extremely susceptible to extinction from both random and 
nonrandom catastrophic natural or human-caused events. Species that are 
restricted to geographically limited areas are inherently more 
vulnerable to extinction than widespread species because of the 
increased risk of genetic bottlenecks, random demographic fluctuations, 
climate change, and localized catastrophes such as hurricanes and 
disease outbreaks (Mangel and Tier 1994, p. 607; Pimm et al. 1998, p. 
757). These problems are further magnified when populations are few and 
restricted to a very small geographic area, and when the number of 
individuals is very small. Populations with these characteristics face 
an increased likelihood of stochastic extinction due to changes in 
demography, the environment, genetics, or other factors (Gilpin and 
Soule 1986, pp. 24-34). Small, isolated populations often exhibit 
reduced levels of genetic variability, which diminishes the species' 
capacity to adapt and respond to environmental changes, thereby 
decreasing the probability of long-term persistence (e.g., Barrett and 
Kohn 1991, p. 4; Newman and Pilson 1997, p. 361). Very small plant 
populations may experience reduced reproductive vigor due to 
ineffective pollination or inbreeding depression. Isolated individuals 
have difficulty achieving natural pollen exchange, which limits the 
production of viable seed. The problems associated with small 
population size and vulnerability to random demographic fluctuations or 
natural catastrophes are further magnified by synergistic interactions 
with other threats, such as those discussed above (see Factors A and 
C).
    Chamaecrista lineata var. keyensis and Chamaesyce deltoidea ssp. 
serpyllum both have large populations on Big Pine Key. The other extant 
occurrence of Chamaecrista lineata var. keyensis in the Florida Keys, 
on Cudjoe Key, is small. Five out of 12 extant Linum arenicola 
populations, and 20 of 34 Argythamnia blodgettii populations have fewer 
than 100 individuals. These small populations are at risk of adverse 
effects from reduced genetic variation, an increased risk of inbreeding 
depression, and reduced reproductive output. Many of these populations 
are small and isolated from each other, decreasing the likelihood that 
they could be naturally reestablished in the event that extinction from 
one location would occur. Argythamnia blodgettii is the only one of the 
four plants species which occurs in ENP, where a population of over 
2,000 plants is stable and prescribed fire and other management 
activities that benefit A. blodgettii are conducted on a regular basis.
Climate Change and Sea Level Rise
    Climatic changes, including sea level rise (SLR), are occurring in 
the State of Florida and are impacting associated plants, animals, and 
habitats. Our analyses under the Act include consideration of ongoing 
and projected changes in climate. The term ``climate,'' as defined by 
the Intergovernmental Panel on Climate Change (IPCC), refers to the 
mean and variability of different types of weather conditions over 
time, with 30 years being a typical period for such measurements, 
although shorter or longer periods also may be used (IPCC 2013, p. 
1450). The term ``climate change'' thus refers to a change in the mean 
or variability of one or more measures of climate (e.g., temperature or 
precipitation) that persists for an extended period, typically decades 
or longer, whether the change is due to natural variability, human 
activity, or both (IPCC 2013, p. 1450). A recent compilation of climate 
change and its effects is available from reports of the 
Intergovernmental Panel on Climate Change (IPCC) (IPCC 2013, entire).
    Scientific measurements spanning several decades demonstrate that 
changes in climate are occurring, and that the rate of change has been 
faster since the 1950s. Examples include warming of the global climate 
system, and substantial increases in precipitation in some regions of 
the world and decreases in other regions. (For these and other 
examples, see IPCC 2007a, p. 30; Solomon et al. 2007, pp. 35-54, 82-
85). Results of scientific analyses presented by the IPCC show that 
most of the observed increase in global average temperature since the 
mid-20th century cannot be explained by natural variability in climate, 
and is ``very likely'' (defined by the IPCC as 90 percent or higher 
probability) due to the observed increase in greenhouse gas (GHG) 
concentrations in the atmosphere

[[Page 58560]]

as a result of human activities, particularly carbon dioxide emissions 
from use of fossil fuels (IPCC 2007a, pp. 5-6 and figures SPM.3 and 
SPM.4; Solomon et al. 2007, pp. 21-35). Further confirmation of the 
role of GHGs comes from analyses by Huber and Knutti (2011, p. 4), who 
concluded it is extremely likely that approximately 75 percent of 
global warming since 1950 has been caused by human activities.
    Scientists use a variety of climate models, which include 
consideration of natural processes and variability, as well as various 
scenarios of potential levels and timing of GHG emissions, to evaluate 
the causes of changes already observed and to project future changes in 
temperature and other climate conditions (e.g., Meehl et al. 2007, 
entire; Ganguly et al. 2009, pp. 11555, 15558; Prinn et al. 2011, pp. 
527, 529). All combinations of models and emissions scenarios yield 
very similar projections of increases in the most common measure of 
climate change, average global surface temperature (commonly known as 
global warming), until about 2030. Although projections of the 
magnitude and rate of warming differ after about 2030, the overall 
trajectory of all the projections is one of increased global warming 
through the end of this century, even for the projections based on 
scenarios that assume that GHG emissions will stabilize or decline. 
Thus, there is strong scientific support for projections that warming 
will continue through the 21st century, and that the magnitude and rate 
of change will be influenced substantially by the extent of GHG 
emissions (IPCC 2007a, pp. 44-45; Meehl et al. 2007, pp. 760-764, 797-
811; Ganguly et al. 2009, pp. 15555-15558; Prinn et al. 2011, pp. 527, 
529). (See IPCC 2007b, p. 8, for a summary of other global projections 
of climate-related changes, such as frequency of heat waves and changes 
in precipitation. Also see IPCC 2011 (entire) for a summary of 
observations and projections of extreme climate events.)
    Various changes in climate may have direct or indirect effects on 
species. These effects may be positive, neutral, or negative, and they 
may change over time, depending on the species and other relevant 
considerations, such as interactions of climate with other variables 
(e.g., habitat fragmentation) (IPCC 2007, pp. 8-14, 18-19). Identifying 
likely effects often involves aspects of climate change vulnerability 
analysis. Vulnerability refers to the degree to which a species (or 
system) is susceptible to, and unable to cope with, adverse effects of 
climate change, including climate variability and extremes. 
Vulnerability is a function of the type, magnitude, and rate of climate 
change and variation to which a species is exposed, its sensitivity, 
and its adaptive capacity (IPCC 2007a, p. 89; see also Glick et al. 
2011, pp. 19-22). There is no single method for conducting such 
analyses that applies to all situations (Glick et al. 2011, p. 3). We 
use our expert judgment and appropriate analytical approaches to weigh 
relevant information, including uncertainty, in our consideration of 
various aspects of climate change.
    As is the case with all stressors that we assess, even if we 
conclude that a species is currently affected or is likely to be 
affected in a negative way by one or more climate-related impacts, it 
does not necessarily follow that the species meets the definition of an 
``endangered species'' or a ``threatened species'' under the Act. If a 
species is listed as endangered or threatened, knowledge regarding the 
vulnerability of the species to, and known or anticipated impacts from, 
climate-associated changes in environmental conditions can be used to 
help devise appropriate strategies for its recovery.
    Global climate projections are informative, and, in some cases, the 
only or the best scientific information available for us to use. 
However, projected changes in climate and related impacts can vary 
substantially across and within different regions of the world (e.g., 
IPCC 2007a, pp. 8-12). Therefore, we use ``downscaled'' projections 
when they are available and have been developed through appropriate 
scientific procedures, because such projections provide higher 
resolution information that is more relevant to spatial scales used for 
analyses of a given species (see Glick et al. 2011, pp. 58-61, for a 
discussion of downscaling).
    With regard to our analysis for Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia 
blodgettii, downscaled projections suggest that SLR is the largest 
climate-driven challenge to low-lying coastal areas in the subtropical 
ecoregion of southern Florida (U.S. Climate Change Science Program 
(USCCSP) 2008, pp. 5-31, 5-32). All populations of the four plants 
occur at elevations from 2.83-4.14 m (9.29-13.57 ft) above sea level, 
making these plants highly susceptible to increased storm surges and 
related impacts associated with SLR.
    We acknowledge that the drivers of SLR (especially contributions of 
melting glaciers) are not completely understood, and there is 
uncertainty with regard to the rate and amount of SLR. This uncertainty 
increases as projections are made further into the future. For this 
reason, we examine threats to the species within the range of 
projections found in recent climate change literature.
    The long-term record at Key West shows that sea level rose on 
average 0.229 cm (0.090 in) annually between 1913 and 2013 (National 
Oceanographic and Atmospheric Administration (NOAA) 2013, p. 1). This 
equates to approximately 22.9 cm (9.02 in) over the last 100 years. 
IPCC (2008, p. 28) emphasized it is very likely that the average rate 
of SLR during the 21st century will exceed the historical rate. The 
IPCC Special Report on Emission Scenarios (2000, entire) presented a 
range of scenarios based on the computed amount of change in the 
climate system due to various potential amounts of anthropogenic 
greenhouse gases and aerosols in 2100. Each scenario describes a future 
world with varying levels of atmospheric pollution leading to 
corresponding levels of global warming and corresponding levels of SLR. 
The IPCC Synthesis Report (2007, entire) provided an integrated view of 
climate change and presented updated projections of future climate 
change and related impacts under different scenarios.
    Subsequent to the 2007 IPCC Report, the scientific community has 
continued to model SLR. Recent peer-reviewed publications indicate a 
movement toward increased acceleration of SLR. Observed SLR rates are 
already trending along the higher end of the 2007 IPCC estimates, and 
it is now widely held that SLR will exceed the levels projected by the 
IPCC (Rahmstorf et al. 2012, p. 1; Grinsted et al. 2010, p. 470). Taken 
together, these studies support the use of higher end estimates now 
prevalent in the scientific literature. Recent studies have estimated 
global mean SLR of 1.0-2.0 m (3.3-6.6 ft) by 2100 as follows: 0.75-1.90 
m (2.50-6.20 ft; Vermeer and Rahmstorf 2009, p. 21530); 0.8-2.0 m (2.6-
6.6 ft; Pfeffer et al. 2008, p. 1342); 0.9-1.3 m (3.0-4.3 ft; Grinsted 
et al. 2010, pp. 469-470); 0.6-1.6 m (2.0-5.2 ft; Jevrejeva et al. 
2010, p. 4); and 0.5-1.4 m (1.6-4.6 ft; National Research Council 2012, 
p. 2).
    Other processes expected to be affected by projected warming 
include temperatures, rainfall (amount, seasonal timing, and 
distribution), and storms (frequency and intensity) (see 
``Environmental Stochasticity'', above). Models where sea surface 
temperatures are increasing also show a higher probability of more 
intense storms (Maschinski et al. 2011, p. 148). The

[[Page 58561]]

Massachusetts Institute of Technology (MIT) modeled several scenarios 
combining various levels of SLR, temperature change, and precipitation 
differences with human population growth, policy assumptions, and 
conservation funding changes. All of the scenarios, from small climate 
change shifts to major changes, indicate significant effects on coastal 
Miami-Dade County. The Science and Technology Committee of the Miami-
Dade County Climate Change Task Force (Wanless et al. 2008, p. 1) 
recognizes that significant SLR is a serious concern for Miami-Dade 
County in the near future. In a January 2008 statement, the committee 
warned that sea level is expected to rise at least 0.9-1.5 m (3.0-5.0 
ft) within this century (Wanless et al. 2008, p. 3). With a 0.9-1.2 m 
(3.0-4.0 ft) rise in sea level (above baseline) in Miami-Dade County, 
spring high tides would be at about 1.83-2.13 m (6.0-7.0 ft); 
freshwater resources would be gone; the Everglades would be inundated 
on the west side of Miami-Dade County; the barrier islands would be 
largely inundated; storm surges would be devastating to coastal habitat 
and associated species; and landfill sites would be exposed to erosion, 
contaminating marine and coastal environments. Freshwater and coastal 
mangrove wetlands will be unable to keep up with or offset SLR of 0.61 
m (2.0 ft) per century or greater. With a 1.52 m (5.0 ft) rise, Miami-
Dade County will be extremely diminished (Wanless et al. 2008, pp. 3-
4).
    SLR projections from various scenarios have been downscaled by TNC 
(2011; entire) and Zhang et al. (2011; entire) for the Florida Keys. 
Using the IPCC best-case, low pollution scenario, a rise of 18 cm (7 
in) (a rate close to the historical average reported above) would 
result in the inundation of 23,796 ha (58,800 acres) or 38.2 percent of 
the Florida Keys upland area by the year 2100 (TNC 2011, p. 25). Under 
the IPCC worst-case, high pollution scenario, a rise of 59 cm (23.2 in) 
would result in the inundation of 46,539 ha (115,000 acres) or 74.7 
percent of the Florida Keys upland area by the year 2100 (TNC 2011, p. 
25). Using Rahmstorf et al.'s (2007; p. 368) SLR projections of 100 to 
140 cm, 80.5 to 92.2 percent of the Florida Keys land area would be 
inundated by 2100. The Zhang et al. (2011, p. 136) study models SLR up 
to 1.8 m (5.9 ft) for the Florida Keys, which would inundate 93.6 
percent of the current land area of the Keys.
    Prior to inundations from SLR, there will likely be habitat 
transitions related to climate change, including changes to hydrology 
and increasing vulnerability to storm surge. Hydrology has a strong 
influence on plant distribution in coastal areas (IPCC 2008, p. 57). 
Such communities typically grade from salt to brackish to freshwater 
species. From the 1930s to 1950s, increased salinity contributed to the 
decline of cabbage palm forests in southwest Florida (Williams et al. 
1999, pp. 2056-2059), expansion of mangroves into adjacent marshes in 
the Everglades (Ross et al. 2000, pp. 101, 111), and loss of pine 
rocklands in the Keys (Ross et al. 1994, pp. 144, 151-155). In Florida, 
pine rocklands transition into rockland hammocks, and, as such, these 
habitat types are closely associated in the landscape. A study 
conducted in one pine rocklands location on Sugar Loaf Key (with an 
average elevation of 0.89 m (2.90 ft)) found an approximately 65 
percent reduction in an area occupied by South Florida slash pine over 
a 70-year period, with pine mortality and subsequent increased 
proportions of halophytic (salt-loving) plants occurring earlier at the 
lower elevations (Ross et al. 1994, pp. 149-152). During this same time 
span, local sea level had risen by 15 cm (6 in), and Ross et al. (1994, 
p. 152) found evidence of groundwater and soil water salinization. 
Extrapolating this situation to hardwood hammocks is not 
straightforward, but it suggests that changes in rockland hammock 
species composition may not be an issue in the immediate future (5-10 
years); however, over the long term (within the next 10-50 years), it 
may be an issue if current projections of SLR occur and freshwater 
inputs are not sufficient to maintain high humidities and prevent 
changes in existing canopy species through salinization (Saha et al. 
2011, pp. 22-25). Ross et al. (2009, pp. 471-478) suggested that 
interactions between SLR and pulse disturbances (e.g., storm surges) 
can cause vegetation to change sooner than projected based on sea level 
alone.
    Impacts from climate change including regional SLR have been 
studied for coastal hammocks but not rockland hammock habitat. Saha (et 
al. 2011, pp. 24-25) conducted a risk assessment on rare plant species 
in ENP and found that impacts from SLR have significant effects on 
imperiled taxa. This study also predicted a decline in the extent of 
coastal hammocks with initial SLR, coupled with a reduction in 
freshwater recharge volume and an increase in pore water (water filling 
spaces between grains of sediment) salinity, which will push hardwood 
species to the edge of their drought (freshwater shortage and 
physiological) tolerance, jeopardizing critically imperiled or endemic 
species, or both, with possible extirpation. In south Florida, SLR of 
1-2 m (3.3-6.6 ft) is estimated by 2100, which is on the higher end of 
global estimates for SLR. These projected increases in sea level pose a 
threat to coastal plant communities and habitats from mangroves at sea 
level to salinity-intolerant, coastal rockland hammocks where 
elevations are generally less than 2.00 m (6.1 ft) above sea level 
(Saha et al. 2011, p. 2). Loss or degradation of these habitats can be 
a direct result of SLR or in combination of several other factors, 
including diversion of freshwater flow, hurricanes, and exotic plant 
species infestations, which can ultimately pose a threat to rare plant 
populations (Saha et al. 2011, p. 24).
    Habitats for these species are restricted to relatively immobile 
geologic features separated by large expanses of flooded, inhospitable 
wetland or ocean, leading us to conclude that these habitats will 
likely not be able to migrate as sea level rises (Saha et al. 2011, pp. 
103-104). Because of the extreme fragmentation of remaining habitat and 
isolation of remaining populations, and the accelerating rate at which 
SLR is projected to occur (Grinsted et al. 2010, p. 470), it will be 
particularly difficult for these species to disperse to suitable 
habitat once existing sites that support them are lost to SLR. Patterns 
of development will also likely be significant factors influencing 
whether natural communities can move and persist (IPCC 2008, p. 57; 
CCSP 2008, pp. 7-6). The plant species face significant risks from 
coastal squeeze that occurs when habitat is pressed between rising sea 
levels and coastal development that prevents landward migration of 
species. The ultimate effect of these impacts is likely to result in 
reductions in reproduction and survival, and corresponding decreases in 
population numbers.
    Saha (et al. 2011, p. 4) suggested that the rising water table 
accompanying SLR will shrink the vadose zone (the area which extends 
from the top of the ground surface to the water table); increase 
salinity in the bottom portion of the freshwater lens, thereby 
increasing brackishness of plant-available water; and influence tree 
species composition of coastal hardwood hammocks based upon species-
level tolerance to salinity or drought or both. Evidence of population 
declines and shifts in rare plant communities, along with multi-trophic 
effects, already have been documented on the low-elevation islands of 
the

[[Page 58562]]

Florida Keys (Maschinski et al. 2011, p. 148).
    Direct losses to extant populations of all four plants are expected 
due to habitat loss and modification from SLR by 2100. We analyzed 
existing sites that support populations of the four plants using the 
National Oceanic and Atmospheric Administration (NOAA) Sea Level Rise 
and Coastal Impacts viewer. Below we discuss general implications of 
sea level rise within the range of projections discussed above on the 
current distribution of these species. The NOAA tool uses 1-foot 
increments, so the analysis is based on 0.91 m (3 ft) and 1.8 m (6 ft).
    Chamaecrista lineata var. keyensis: A 0.91-m (3-ft) rise would 
inundate most areas of Big Pine Key, and all areas of Cudjoe Key, that 
support Chamaecrista lineata var. keyensis, and reduce both Keys to 
several much smaller islands. The remaining uplands on these islands 
would likely transition to buttonwoods and saltmarshes, and would be 
extremely vulnerable to storm surge. This will further reduce and 
fragment these populations. A 1.8-m (6-ft) rise would completely 
inundate all areas that support C. lineata var. keyensis and eliminate 
all pine rocklands habitat within the historic range of the species.
    Chamaesyce deltoidea var. serpyllum: A 0.91-m (3-ft) rise would 
inundate most areas of Big Pine Key that support Chamaesyce deltoidea 
var. serpyllum, and reduce the Key to three to five much smaller 
islands. The remaining uplands would likely transition to buttonwoods 
and saltmarshes, and would be extremely vulnerable to storm surge. This 
will further reduce and fragment the population. A 1.8-m (6-ft) rise 
would completely inundate all areas that support C. deltoidea var. 
serpyllum and eliminate all pine rocklands habitat within the historic 
range of the species.
    Linum arenicola: In Miami-Dade County, a 0.91-m (3-ft) rise would 
inundate the area that supports a large extant population of Linum 
arenicola along L-31E canal. While other areas that support the species 
are located in higher elevation areas along the coastal ridge, changes 
in the salinity of the water table and soils, along with additional 
vegetation shifts in the region, are likely. Remaining uplands may 
transition to wetter, more salt-tolerant plant communities. This will 
further reduce and fragment the populations. A 1.8-m (6-ft) rise would 
inundate portions of the largest known population (HARB), as well the 
population along L-31E canal. The areas that support Linum arenicola at 
the Martinez and Richmond pinelands to the north would not be 
inundated, but pine rocklands in these areas may be reduced through 
transition to wetter, more salt-tolerant plant communities, as 
discussed above.
    In the Florida Keys, a 0.91-m (3-ft) rise would inundate most areas 
of Big Pine Key and Lower Sugarloaf Key, and all of the areas on Upper 
Sugarloaf Key and Big Torch Key, that support Linum arenicola, and 
reduce these Keys to numerous much smaller islands. The remaining 
uplands on these small islands would likely transition to buttonwoods 
and saltmarshes, and would be extremely vulnerable to further losses 
due to storm surge. This would further reduce and fragment the 
populations. A 1.8-m (6-ft) rise would completely inundate all areas 
that support Linum arenicola in the Florida Keys and eliminate all pine 
rocklands habitat within the historic range of the species in Monroe 
County.
    Argythamnia blodgettii: In Miami-Dade County, a 0.91-m (3-ft) rise 
would not inundate any extant populations of Argythamnia blodgettii 
because these habitats are located in higher elevation areas along the 
coastal ridge. However, changes in the salinity of the water table and 
soils, along with additional vegetation shifts in the region, are 
likely. Remaining uplands may likely transition to wetter, more salt-
tolerant plant communities. This will further reduce and fragment the 
populations. A 1.8-m (6-ft) rise would inundate portions of Crandon 
Park, making it unsuitable for A. blodgettii. Other areas that support 
A. blodgettii, including the Martinez and Richmond pinelands to the 
north, and Long Pine Key in ENP, would not be inundated, but habitats 
in these areas may be reduced through transition to wetter, more salt-
tolerant plant communities, as discussed above.
    In the Florida Keys, a 0.91-m (3-ft) rise would reduce the area of 
islands in the upper Keys, but extant populations on Key Largo, Windley 
Key, and Lignumvitae Key are less vulnerable than the Middle and Lower 
Keys, which are at lower elevations. Lower Matecumbe Key, Plantation 
Key, Vaca Key, Big Pine Key, and Big Munson Island would be fragmented 
and reduced to numerous much smaller islands. The remaining uplands on 
these small islands would likely transition to buttonwoods and 
saltmarshes, and would be extremely vulnerable further losses to storm 
surge. This would further reduce and fragment the populations. A 1.8-m 
(6-ft) rise would completely inundate all areas that support 
Argythamnia blodgettii south of Lignumvitae Key. Key Largo, Windley 
Key, and Lignumvitae Key are the only existing areas supporting extant 
populations that could continue to support a population given a 1.8-m 
(5.9-ft) sea level rise.
Conservation Efforts To Reduce Other Natural or Manmade Factors 
Affecting Its Continued Existence
    NPS, the Service, Miami-Dade County, and the State of Florida have 
ongoing nonnative plant management programs to reduce threats on public 
lands, as funding and resources allow. In Miami-Dade County, nonnative, 
invasive plant management is very active, with a goal to treat all 
publicly owned properties at least once a year and more often in many 
cases. IRC and FTBG conduct research and monitoring in various natural 
areas within Miami-Dade County and the Florida Keys for various 
endangered plant species and nonnative, invasive species.
Summary of Factor E
    We have analyzed threats from other natural or manmade factors 
including: nonnative, invasive plants; management practices used on 
roadsides and disturbed sites (such as mowing, sodding, and herbicide 
use); pesticide spraying and its effects on pollinators; environmental 
stochasticity; effects from small population size and isolation; and 
the effects of climate change, including SLR. The related risks from 
hurricanes and storm surge act together to impact populations of all 
four plants. Some of these threats (e.g., nonnative species) may be 
reduced on public lands due to active programs by Federal, State, and 
county land managers. Many of the remaining populations of these plants 
are small and geographically isolated, and genetic variability is 
likely low, increasing the inherent risk due to overall low resilience 
of these plants.

Cumulative Effects of Threats

    When two or more threats affect populations of the four plants, the 
effects of those threats could interact or become compounded, producing 
a cumulative adverse effect that is greater than the impact of either 
threat alone. The most obvious cases in which cumulative adverse 
effects would be significant are those in which small populations 
(Factor E) are affected by threats that result in destruction or 
modification of habitat (Factor A). The limited distributions and small 
population sizes of many populations of the four plants make them 
extremely susceptible to the detrimental effects of further habitat 
modification, degradation, and loss, as well as other anthropogenic 
threats. Mechanisms

[[Page 58563]]

leading to the decline of the four plants, as discussed above, range 
from local (e.g., agriculture) to regional (e.g., development, 
fragmentation, nonnative species) to global influences (e.g., climate 
change, SLR). The synergistic effects of threats, such as impacts from 
hurricanes on a species with a limited distribution and small 
populations, make it difficult to predict population viability. While 
these stressors may act in isolation, it is more probable that many 
stressors are acting simultaneously (or in combination) on populations 
of these four plants, making them more vulnerable.

Proposed Determination

    We have carefully assessed the best scientific and commercial data 
available regarding the past, present, and future threats to 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii. Numerous 
populations of all four plants have been extirpated from these species' 
historical ranges, and the primary threats of habitat destruction and 
modification resulting from human population growth and development, 
agricultural conversion, and inadequate fire management (Factor A); 
competition from nonnative, invasive species (Factor E); changes in 
climatic conditions, including SLR (Factor E); and natural stochastic 
events (Factor E) remain threats for existing populations. Existing 
regulatory mechanisms have not led to a reduction or removal of threats 
posed to the four plants from these factors (see Factor D discussion, 
above). These threats are ongoing, rangewide, and expected to continue 
in the future. A significant percentage of populations of Chamaecrista 
lineata var. keyensis, Linum arenicola, and Argythamnia blodgettii are 
relatively small and isolated from one another, and their ability to 
recolonize suitable habitat is unlikely without human intervention, if 
at all. The threats have had and will continue to have substantial 
adverse effects on the four plants and their habitats. Although 
attempts are ongoing to alleviate or minimize some of these threats at 
certain locations, all populations appear to be impacted by one or more 
threats.
    The Act defines an endangered species as ``any species which is in 
danger of extinction throughout all or a significant portion of its 
range'' and a threatened species as ``any species which is likely to 
become an endangered species within the foreseeable future throughout 
all or a significant portion of its range.''
    As described in detail above, Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, and Linum arenicola are currently 
at risk throughout all of their range due to the immediacy, severity, 
significance, timing, and scope of those threats. Impacts from these 
threats are ongoing and increasing; singly or in combination, these 
threats place these three plants in danger of extinction. The risk of 
extinction is high because the populations are small, are isolated, and 
have limited to no potential for recolonization. Numerous threats are 
currently ongoing and are likely to continue in the foreseeable future, 
at a high intensity and across the entire range of these plants. 
Furthermore, natural stochastic events and changes in climatic 
conditions pose a threat to the persistence of these plants, especially 
in light of the fact these events cannot be controlled and mitigation 
measures have yet to be addressed. Individually and collectively, all 
these threats can contribute to the local extirpation and potential 
extinction of these plant species. Because these threats are placing 
them in danger of extinction throughout their ranges, we have 
determined that each of these three plants meets the definition of an 
endangered species. Therefore, on the basis of the best available 
scientific and commercial information, we propose to list Chamaecrista 
lineata var. keyensis, Chamaesyce deltoidea ssp. serpyllum, and Linum 
arenicola as endangered species in accordance with sections 3(6) and 
4(a)(1) of the Act. We find that threatened species status is not 
appropriate for Chamaecrista lineata var. keyensis, Chamaesyce 
deltoidea ssp. serpyllum, and Linum arenicola because of the contracted 
range of each species and because the threats are occurring rangewide, 
are ongoing, and are expected to continue into the future.
    Throughout its range, Argythamnia blodgettii faces threats similar 
to the other three plant species that are the subjects of this proposed 
rule. However, we find that endangered species status is not 
appropriate for A. blodgettii. While we have evidence of threats under 
Factors A, D, and E affecting the species, insufficient data are 
available to identify the trends in extant populations. Six populations 
are extant, 11 are extirpated, and we are uncertain of the status of 14 
populations that have not been surveyed in 15 years or more. 
Additionally, data show that the threat of habitat loss from sea level 
rise is not as severe for this species. Also, A. blodgettii is likely 
less vulnerable because of the larger number of sites where it occurs 
throughout Miami-Dade and Monroe Counties. Further, A. blodgettii is 
the only one of the four plants species that occurs in ENP, where a 
population of over 2,000 plants is stable and prescribed fire and other 
management activities that benefit A. blodgettii are conducted on a 
regular basis. Therefore, based on the best available information, we 
find that A. blodgettii is likely to become an endangered species 
within the foreseeable future throughout all or a significant portion 
of its range, and we propose to list the species as a threatened 
species in accordance with sections 3(20) and 4(a)(1) of the Act.

Significant Portion of the Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is endangered or threatened throughout all or a 
significant portion of its range. The threats to the survival of 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii occur throughout 
these species' ranges and are not restricted to any particular 
significant portion of those ranges. Accordingly, our assessment and 
proposed determination applies to each of the four plants throughout 
its entire range. Because we have determined that Chamaecrista lineata 
var. keyensis, Chamaesyce deltoidea ssp. serpyllum, and Linum arenicola 
meet the definition of endangered species, and Argythamnia blodgettii 
meets the definition of a threatened species, throughout their ranges, 
no portion of their ranges can be ``significant'' for purposes of the 
definitions of ``endangered species'' and ``threatened species.'' See 
the Service's SPR Policy (79 FR 37578, July 1, 2014).

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
practices. Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies; private 
organizations; and individuals. The Act encourages cooperation with the 
States and other countries and calls for recovery actions to be carried 
out for listed species. The protection required by Federal agencies and 
the prohibitions against certain activities are discussed, in part, 
below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate

[[Page 58564]]

goal of such conservation efforts is the recovery of these listed 
species, so that they no longer need the protective measures of the 
Act. Subsection 4(f) of the Act calls for the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The recovery planning process involves the 
identification of actions that are necessary to halt or reverse the 
species' decline by addressing the threats to its survival and 
recovery. The goal of this process is to restore listed species to a 
point where they are secure, self-sustaining, and functioning 
components of their ecosystems.
    Recovery planning includes the development of a recovery outline 
shortly after a species is listed and preparation of a draft and final 
recovery plan. The recovery outline guides the immediate implementation 
of urgent recovery actions and describes the process to be used to 
develop a recovery plan. Revisions of the plan may be done to address 
continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan also identifies 
recovery criteria for review of when a species may be ready for 
downlisting or delisting, and methods for monitoring recovery progress. 
Recovery plans also establish a framework for agencies to coordinate 
their recovery efforts and provide estimates of the cost of 
implementing recovery tasks. Recovery teams (composed of species 
experts, Federal and State agencies, nongovernmental organizations, and 
stakeholders) are often established to develop recovery plans. If these 
four plant species are listed, a recovery outline, draft recovery plan, 
and the final recovery plan will be available on our Web site (https://www.fws.gov/endangered), or from our South Florida Ecological Services 
Field Office (see FOR FURTHER INFORMATION CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands. 
If these four plant species are listed, funding for recovery actions 
will be available from a variety of sources, including Federal budgets, 
State programs, and cost share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the State of Florida would be 
eligible for Federal funds to implement management actions that promote 
the protection or recovery of the four plants. Information on our grant 
programs that are available to aid species recovery can be found at: 
https://www.fws.gov/grants.
    Although Chamaecrista lineata var. keyensis, Chamaesyce deltoidea 
ssp. serpyllum, Linum arenicola, and Argythamnia blodgettii are only 
proposed for listing under the Act at this time, please let us know if 
you are interested in participating in recovery efforts for this 
species. Additionally, we invite you to submit any new information on 
these plants whenever it becomes available and any information you may 
have for recovery planning purposes (see FOR FURTHER INFORMATION 
CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is proposed or listed as an 
endangered or threatened species and with respect to its critical 
habitat, if any is designated. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Section 7(a)(4) of the Act requires Federal agencies to 
confer with the Service on any action that is likely to jeopardize the 
continued existence of a species proposed for listing or result in 
destruction or adverse modification of proposed critical habitat, if 
designated. If a species is listed subsequently, section 7(a)(2) of the 
Act requires Federal agencies to ensure that activities they authorize, 
fund, or carry out are not likely to jeopardize the continued existence 
of the species or destroy or adversely modify its critical habitat. If 
a Federal action may affect a listed species or its critical habitat, 
if designated, the responsible Federal agency must enter into 
consultation with the Service.
    Federal agency actions within the species' habitat that may require 
conference or consultation or both as described in the preceding 
paragraph include management and any other landscape-altering 
activities on Federal lands administered by the Service, NPS, and 
Department of Defense; issuance of section 404 Clean Water Act permits 
by the U.S. Army Corps of Engineers; construction and management of gas 
pipeline and power line rights-of-way by the Federal Energy Regulatory 
Commission; construction and maintenance of roads or highways by the 
Federal Highway Administration; and disaster relief efforts conducted 
by the Federal Emergency Management Agency.
    With respect to endangered plants, prohibitions outlined at 50 CFR 
17.61 make it illegal for any person subject to the jurisdiction of the 
United States to import or export, transport in interstate or foreign 
commerce in the course of a commercial activity, sell or offer for sale 
in interstate or foreign commerce, or to remove and reduce to 
possession any such plant species from areas under Federal 
jurisdiction. In addition, for endangered plants, the Act prohibits 
malicious damage or destruction of any such species on any area under 
Federal jurisdiction, and the removal, cutting, digging up, or damaging 
or destroying of any such species on any other area in knowing 
violation of any State law or regulation, or in the course of any 
violation of a State criminal trespass law. Exceptions to these 
prohibitions are outlined in 50 CFR 17.62. With respect to threatened 
plants, 50 CFR 17.71 provides that, with certain exceptions, all of the 
prohibitions outlined at 50 CFR 17.61 for endangered plants also apply 
to threatened plants. Permit exceptions to the prohibitions for 
threatened plants are outlined in 50 CFR 17.72.
    Preservation of native flora of Florida through Florida Statutes 
581.185, sections (3)(a) and (3)(b), provide limited protection to 
species listed in the State of Florida Regulated Plant Index including 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii, as described 
under the Factor D discussion, above. Federal listing would increase 
protection for these plants by making violations of section 3 of the 
Florida Statute punishable as a Federal offense under section 9 of the 
Act. This would provide increased protection from unauthorized 
collecting and vandalism for the plants on State and private lands, 
where they might not otherwise be protected by the Act, and would 
increase the severity of the penalty for unauthorized collection, 
vandalism, or trade in these plants.
    The Service acknowledges that it cannot fully address some of the 
natural threats facing Chamaecrista lineata var. keyensis, Chamaesyce 
deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia blodgettii, 
(e.g., hurricanes, storm surge) or even some of the other significant, 
long-term threats (e.g., climatic changes, SLR). However,

[[Page 58565]]

through listing, we could provide protection to the known populations 
and any new population of these plants that may be discovered (see 
discussion below). With listing, we could also influence Federal 
actions that may potentially impact these plants (see discussion 
below); this is especially valuable if these plants are found at 
additional locations. With listing, we would also be better able to 
deter illicit collection and trade.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered or threatened plants under certain circumstances. 
Regulations governing permits for endangered plants are codified at 50 
CFR 17.62, and for threatened plants at 50 CFR 17.72. With regard to 
endangered plants, the Service may issue a permit authorizing any 
activity otherwise prohibited by 50 CFR 17.61 for scientific purposes 
or for enhancing the propagation or survival of endangered plants.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is proposed for listing or listed, those activities 
that would or would not constitute a violation of section 9 of the Act. 
The intent of this policy is to increase public awareness of the effect 
of a proposed listing on proposed and ongoing activities within the 
range of species proposed for listing. Based on the best available 
information, the following actions would be unlikely to result in a 
violation of section 9, if these activities were carried out in 
accordance with existing regulations and permit requirements; this list 
is not comprehensive:
    (1) Import any such species into, or export any of the four plant 
species from, the United States.
    (2) Remove and reduce to possession any of the four plant species 
from areas under Federal jurisdiction; maliciously damage or destroy 
any of the four plant species on any such area; or remove, cut, dig up, 
or damage or destroy any of the four plant species on any other area in 
knowing violation of any law or regulation of any State or in the 
course of any violation of a State criminal trespass law.
    (3) Deliver, receive, carry, transport, or ship in interstate or 
foreign commerce, by any means whatsoever and in the course of a 
commercial activity, any of the four plant species.
    (4) Sell or offer for sale in interstate or foreign commerce any of 
the four plant species.
    (5) Introduce any nonnative wildlife or plant species to the State 
of Florida that compete with or prey upon Chamaecrista lineata var. 
keyensis, Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, or 
Argythamnia blodgettii.
    (6) Release any unauthorized biological control agents that attack 
any life stage of Chamaecrista lineata var. keyensis, Chamaesyce 
deltoidea ssp. serpyllum, Linum arenicola, or Argythamnia blodgettii.
    (7) Manipulate or modify, without authorization, the habitat of 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, or Argythamnia blodgettii on Federal lands.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Field 
Supervisor of the Service's South Florida Ecological Services Field 
Office (see FOR FURTHER INFORMATION CONTACT). Requests for copies of 
regulations regarding listed species and inquiries about prohibitions 
and permits should be addressed to the U.S. Fish and Wildlife Service, 
Ecological Services Division, Endangered Species Permits, 1875 Century 
Boulevard, Atlanta, GA 30345 (phone 404-679-7140; fax 404-679-7081).
    If Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii are listed under 
the Act, the State of Florida's Endangered Species Act (Florida 
Statutes 581.185) is automatically invoked, which would also prohibit 
take of these plants and encourage conservation by State government 
agencies. Further, the State may enter into agreements with Federal 
agencies to administer and manage any area required for the 
conservation, management, enhancement, or protection of endangered 
species (Florida Statutes 581.185). Funds for these activities could be 
made available under section 6 of the Act (Cooperation with the 
States). Thus, the Federal protection afforded to these plants by 
listing them as endangered species would be reinforced and supplemented 
by protection under State law.
    Activities that the Service believes could potentially harm these 
four plants include, but are not limited to:
    (1) Actions that would significantly alter the hydrology or 
substrate, such as ditching or filling. Such activities may include, 
but are not limited to, road construction or maintenance, and 
residential, commercial, or recreational development.
    (2) Actions that would significantly alter vegetation structure or 
composition, such as clearing vegetation for construction of 
residences, facilities, trails, and roads.
    (3) Actions that would introduce nonnative species that would 
significantly alter vegetation structure or composition. Such 
activities may include, but are not limited to, residential and 
commercial development, and road construction.
    (4) Application of herbicides, or release of contaminants, in areas 
where these plants occur. Such activities may include, but are not 
limited to, natural resource management, management of right of ways, 
residential and commercial development, and road construction.

Critical Habitat

    Section 3(5)(A) of the Act defines critical habitat as ``(i) the 
specific areas within the geographical area occupied by the species, at 
the time it is listed * * * on which are found those physical or 
biological features (I) essential to the conservation of the species 
and (II) which may require special management considerations or 
protection; and (ii) specific areas outside the geographical area 
occupied by the species at the time it is listed upon a determination 
by the Secretary that such areas are essential for the conservation of 
the species. Section 3(3) of the Act defines conservation as to use and 
the use of all methods and procedures which are necessary to bring any 
endangered species or threatened species to the point at which the 
measures provided pursuant to the Act are no longer necessary.''
    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, the Secretary will designate critical habitat 
at the time the species is determined to be an endangered or threatened 
species. Our regulations (50 CFR 424.12(a)(1)) state that the 
designation of critical habitat is not prudent when one or both of the 
following situations exist:
    (1) The species is threatened by taking or other human activity, 
and identification of critical habitat can be expected to increase the 
degree of threat to the species, or
    (2) Such designation of critical habitat would not be beneficial to 
the species.
    There is currently no imminent threat of take attributed to 
collection or vandalism under Factor B for these species, and 
identification and mapping of critical habitat is not expected to 
initiate any such threat. Therefore, in the absence of finding that the 
designation of critical habitat would increase threats to a species, if 
there are

[[Page 58566]]

any benefits to a critical habitat designation, a finding that 
designation is prudent is warranted. Here, the potential benefits of 
designation include: (1) Triggering consultation under section 7 of the 
Act, in new areas for actions in which there may be a Federal nexus 
where it would not otherwise occur because, for example, it is 
unoccupied; (2) focusing conservation activities on the most essential 
features and areas; (3) providing educational benefits to State or 
county governments or private entities; and (4) preventing people from 
causing inadvertent harm to these species.
    Because we have determined that the designation of critical habitat 
will not likely increase the degree of threat to the species and may 
provide some measure of benefit, we determine that designation of 
critical habitat is prudent for Chamaecrista lineata var. keyensis, 
Chamaesyce deltoidea ssp. serpyllum, Linum arenicola, and Argythamnia 
blodgettii.
    Our regulations (50 CFR 424.12(a)(2)) further state that critical 
habitat is not determinable when one or both of the following 
situations exists: (1) Information sufficient to perform required 
analysis of the impacts of the designation is lacking; or (2) the 
biological needs of the species are not sufficiently well known to 
permit identification of an area as critical habitat. On the basis of a 
review of available information, we find that critical habitat for 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, Linum arenicola, and Argythamnia blodgettii is not 
determinable because the specific information sufficient to perform the 
required analysis of the impacts of the designation is currently 
lacking.

Required Determinations

Clarity of the Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (1) Be logically organized;
    (2) Use the active voice to address readers directly;
    (3) Use clear language rather than jargon;
    (4) Be divided into short sections and sentences; and
    (5) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in the ADDRESSES section. To 
better help us revise the rule, your comments should be as specific as 
possible. For example, you should tell us the numbers of the sections 
or paragraphs that are unclearly written, which sections or sentences 
are too long, the sections where you feel lists or tables would be 
useful, etc.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act, need not be prepared in connection with 
listing a species as an endangered or threatened species under the Act. 
We published a notice outlining our reasons for this determination in 
the Federal Register on October 25, 1983 (48 FR 49244).

References Cited

    A complete list of references cited in this rulemaking is available 
on the Internet at https://www.regulations.gov and upon request from the 
South Florida Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT).

Authors

    The primary authors of this proposed rule are the staff members of 
the South Florida Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

    Accordingly, we propose to amend part 17, subchapter B of chapter 
I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17--[AMENDED]

0
1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless 
otherwise noted.

0
2. Amend Sec.  17.12(h) by adding entries for Argythamnia blodgettii, 
Chamaecrista lineata var. keyensis, Chamaesyce deltoidea ssp. 
serpyllum, and Linum arenicola, in alphabetical order under FLOWERING 
PLANTS, to the List of Endangered and Threatened Plants to read as set 
forth below:


Sec.  17.12  Endangered and threatened plants.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                      Species
---------------------------------------------------   Historic range         Family           Status      When listed       Critical      Special rules
        Scientific name             Common name                                                                             habitat
--------------------------------------------------------------------------------------------------------------------------------------------------------
FLOWERING PLANTS
 
                                                                      * * * * * * *
Argythamnia blodgettii.........  Blodgett's         U.S.A. (FL)......  Euphorbiaceae....  T............  .............  NA.............  NA
                                  silverbush.
 
                                                                      * * * * * * *
Chamaecrista lineata var.        Big Pine           U.S.A. (FL)......  Fabaceae.........  E............  .............  NA.............  NA
 keyensis.                        partridge pea.
 
                                                                      * * * * * * *
Chamaesyce deltoidea ssp.        Wedge spurge.....  U.S.A. (FL)......  Euphorbiaceae....  E............  .............  NA.............  NA
 serpyllum.
 
                                                                      * * * * * * *
Linum arenicola................  Sand flax........  U.S.A. (FL)......  Linaceae.........  E............  .............  NA.............  NA
 
                                                                      * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 58567]]

* * * * *

    Dated: September 9, 2015.
Stephen Guertin,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2015-24291 Filed 9-28-15; 8:45 am]
 BILLING CODE 4310-55-P