[Federal Register Volume 70, Number 7 (Tuesday, January 11, 2005)]
[Proposed Rules]
[Pages 1858-1862]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-442]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018--AI79


Endangered and Threatened Wildlife and Plants; Proposed Removal 
of the Plant Agave arizonica (Arizona agave) From the Federal List of 
Endangered and Threatened Plants

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), under the 
Endangered Species Act of 1973, as amended (Act), propose to remove the 
plant Agave arizonica (Arizona agave) from the Federal List of 
Endangered and Threatened Plants. Agave arizonica was listed as 
endangered on June 18, 1984, due to threats of habitat modification and 
collection. Evidence collected subsequent to the listing indicates that 
plants attributed to Agave arizonica do not constitute a distinct 
species but rather are individuals that have resulted from recent and 
sporadic instances of hybridization between two species. Current 
taxonomic practice is not to recognize such groups of individuals as a 
species. The term ``species,'' as defined by the Act, only includes 
species, subspecies, and distinct population segments. Since Agave 
arizonica is not recognized as a species, it no longer qualifies for 
protection under the Act.

DATES: Comments on the proposed rule must be received on or before 
March 14, 2005 to ensure our consideration. Public hearing requests 
must be received by February 25, 2005.

ADDRESSES: Comments and materials concerning this proposal should be 
sent

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to the Field Supervisor, U.S. Fish and Wildlife Service, Arizona 
Ecological Services Field Office, 2321 West Royal Palm Road, Suite 103, 
Phoenix, Arizona 85021-4951. The proposal, supporting data, and 
comments are available for public inspection, by appointment, during 
normal business hours at the above address.

FOR FURTHER INFORMATION CONTACT: Mima Falk, U.S. Fish and Wildlife 
Service, located in the Tucson suboffice, 110 South Church Ave, Suite 
3450, Tucson, Arizona 85701 (telephone (520) 670-6150 ext. 225; 
facsimile (520) 670-6154).

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

    We intend that any final action resulting from this proposal be as 
accurate and as effective as possible. Therefore, comments or 
suggestions from the public, other concerned governmental agencies, the 
scientific community, industry, or any other interested party 
concerning this proposed rule are hereby solicited. Comments 
particularly are sought concerning:
    (1) Biological, commercial trade, or other relevant data concerning 
the taxonomic status or threats (or lack thereof) to this hybrid;
    (2) The location and characteristics of any additional populations 
not considered in previous work that might have bearing on the current 
taxonomic interpretation; and
    (3) Additional information concerning range, distribution, and 
population sizes, particularly if it would assist in the evaluation of 
the accuracy of the current taxonomic interpretation.
    Our practice is to make comments that we receive on this 
rulemaking, including names and home addresses of respondents, 
available for public review during regular business hours. Individual 
respondents may request that we withhold their home address from the 
rulemaking record, which we will honor to the extent allowable by 
Federal law. In some circumstances, we may withhold from the rulemaking 
record a respondent's identity, as allowable by Federal law. If you 
wish for us to withhold your name and/or address, you must state this 
prominently at the beginning of your comment. However, we will not 
consider anonymous comments. We will make all submissions from 
organizations or businesses, including individuals identifying 
themselves as representatives or officials of organizations or 
businesses, available for public inspection in their entirety.
    We will take into consideration the comments and any additional 
information received, and such communications may lead to a final 
regulation that differs from this proposal.

Public Hearing

    The Act provides for one or more public hearings on this proposal, 
if requested. Requests must be received within 45 days of the date of 
publication of the proposal in the Federal Register. Such requests must 
be made in writing and addressed to Field Supervisor (see ADDRESSES 
section).

Background

    Agave arizonica, a member of the agave family, was first discovered 
by J. H. Houzenga, M. J. Hazelett, and J. H. Weber in the New River 
Mountains of Arizona. Drs. H. S. Gentry and J. H. Weber described this 
species in the ``Cactus and Succulent Journal'' in 1970 (Gentry and 
Weber 1970). This perennial succulent has leaves growing from the base 
in a small basal rosette (i.e., an arrangement of leaves radiating from 
a crown or center), and is approximately 20-35 centimeters (cm) (8-14 
inches (in)) high and 30-40 cm (12-16 in) wide. The leaves are dark 
green with a reddish-brown to light gray border extending nearly to the 
base, approximately 13-31 cm (5-12 in) long and 2-3 cm (1 in) wide. The 
slender, branched flowering stalk is 2.5-4 meters (m) (8.2-13 feet 
(ft)) tall with urn-shaped flowers 25-32 millimeters (mm) (1 in) long 
(Hodgson 1999).
    Agave arizonica is found on open slopes in chaparral or juniper 
grassland in Gila, Maricopa, and Yavapai Counties between 1,100-1,750 m 
(3,600-5,800 ft) in elevation. The plants are often found associated 
with Juniperus spp., mountain mahogany (Cercocarpus montanus), Opuntia 
spp., sotol (Nolina microcarpa), and banana yucca (Yucca baccata), 
among other species common to the chaparral/juniper-oak transition 
(Hodgson and DeLamater 1988). There are estimated to be fewer than 100 
plants in the wild, occurring mainly on the Tonto National Forest and a 
few locations on private property. Agave arizonica plants are 
associated with soils that are shallow, cobbled, and gravelly, on 
strongly sloping to very steep slopes and rock outcrops on mid-
elevation hills and mountains. The soils are well-drained and derived 
from a variety of rocks, including granite, gneiss, rhyolite, andesite, 
ruffs, limestone, sandstone, and basalt (Hodgson and DeLamater 1988). 
Plants typically flower in May-July.
    Field studies on Agave arizonica began in 1983. A natural 
distribution study was not finalized until August 1984 (DeLamater 
1984), after the final listing rule (49 FR 21055, May 18, 1984) was 
published. Surveys for this study were conducted in the New River 
Mountains, and by 1984, ten new clones (vegetative offsets, or buds, 
from an individual plant) were found in these mountains. These were 
individual clones of 2-5 rosettes. All of the clones occurred together 
with two other agaves, Agave toumeyana ssp. bella and A. chrysantha. A. 
chrysantha is found in southern and eastern Yavapai Counties, through 
much of Gila and Maricopa Counties, northern and eastern Pinal County, 
and northeastern Pima County. Agave toumeyana ssp. bella is restricted 
to the eastern slope of the Bradshaw Mountains, eastern Yavapai to 
northwestern and central to southern Gila County, northeastern Maricopa 
to northern Pinal County. Neither species is considered rare. A 
comparison of plant characters showed Agave arizonica to be 
intermediate to the other two agave species with which it is always 
found in association (DeLamater and Hodgson 1986). Pinkava and Baker 
(1985) suggested that plants recognized as Agave arizonica may be the 
result of continuing production of hybrid individuals rather than a 
species of hybrid origin based on their occurrence only where the 
ranges of the putative parents overlap; they are found only in random, 
widely scattered locations of individual plants and clones; their 
putative parents have overlapping flowering periods; Agave arizonica's 
morphological characters are intermediate between the putative parents; 
and they appeared to be subfertile (reduced fertilization), producing 
pollen with a low percent of stainability, or viability. Agave 
arizonica has a chromosome count (2n) of 60, as does both its parents, 
indicating that gross chromosomal barriers to backcrossing with the 
putative parents are lacking. Polyploidy (having more than two complete 
sets of homologous chromosomes) is one factor in determining if a 
hybrid between two species can become genetically stable. That 
condition is not present in the genetic constitution of Agave 
arizonica.
    Additional surveys were conducted in areas that supported sympatric 
populations (occurring together) of the putative parents. This resulted 
in the discovery of two clones in the Sierra Ancha Mountains, 100 miles 
disjunct from the New River Mountain locations. To date, plants and 
clones are known from three areas on the Tonto National

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Forest (New River Mountains, Sierra Ancha Mountains, and the Humboldt 
Mountains). These three areas are widely separated from each other. The 
New River population is the most numerous, located 17.94 kilometers 
(km) (10.7 miles (mi)) west-northwest of the Sierra Ancha population. 
The Sierra Ancha population is comprised of one individual (Trabold 
2001). There is another hybrid from the Payson area in the Humboldt 
Mountains. This agave is produced from a cross between A. toumeyana 
ssp. toumeyana X A. chrysantha that is sometimes incorrectly referred 
to as Arizona agave (Pinkava and Baker 1985). That individual is a 
triploid (3n=90), and therefore has a different chromosome count than 
Agave arizonica.
    The Desert Botanical Garden (DBG), in Phoenix, initiated ecological 
studies of Agave arizonica in the mid-1980s through 1994. They 
conducted numerous surveys on the Tonto National Forest, collected 
seeds in situ (outside of confinement), conducted experimental crosses 
in situ and ex situ (in an artificial environment), and started an ex 
situ collection. DBG's work has shown that Agave arizonica can produce 
viable seed. In 1985, three different crosses were performed on clone 
52, in situ, using flowers from different panicles (flower 
stalks). One cross used frozen pollen collected from Agave arizonica at 
the DBG, the second cross was self-fertilization of clone 52, 
and the third cross was uncontrolled outcrossing of clone 52 
(flowers were left open to be pollinated by various donors). Seed was 
collected from all three crosses. Cross 1 produced 250 seeds, 
cross 2 produced 20 seeds, and cross 3 produced a 
large quantity of seeds (Hodgson and DeLamater 1988). Cross 2 
produced poor seed set from self-fertilization, while outcrossing with 
Agave arizonica pollen produced a high proportion of viable seed, as 
did uncontrolled outcrossing. The majority of the seeds were planted. 
Ten months after planting, 10 of the 105 seeds produced from cross 
1 germinated. Some of those resembled Agave arizonica, while 
others did not (W. Hodgson, Desert Botanical Garden, pers. comm. 2003). 
DBG also conducted controlled crosses of A. chrysantha and A. toumeyana 
ssp. bella. The seeds produced from this cross resulted in Agave 
arizonica plants. Individual Agave arizonica plants can therefore be 
created by crosses of the parental species. This condition indicates 
that there is nothing genetically unique about Agave arizonica. If all 
of the Agave arizonica individuals that exist in the field were 
destroyed, it is unlikely that any unique genetic material would be 
lost (M. Baker, Southwest Botanical Research, pers. comm. 2004). These 
results support the hypothesis that Agave arizonica is composed of 
individuals that resulted from recent and spontaneous instances of 
hybridization between two species, and is not, at this time, a species 
of hybrid origin.
    Agave arizonica is most likely a first-generation (F1) hybrid 
between two other species. It is not known if any individuals of the F1 
generation, in situ, have backcrossed with either one of the parents or 
with another Agave arizonica individual. The latter seems unlikely 
because of the distance pollen would have to travel given the low 
numbers of individuals and the great distance separating them. Seeds 
have been produced in the wild, but it is not known if those seeds were 
produced from Agave arizonica X either parent or Agave arizonica X 
Agave arizonica. Seeds grown out in greenhouse conditions produced 
plants with wide phenotypic (visible) variations; not all seedlings 
represented ``pure'' Agave arizonica traits. The fact that Agave 
arizonica can be reliably produced by crossing the putative parents ex 
situ lends support to the hypothesis that Agave arizonica is a 
recurring F1 hybrid. All evidence supports that Agave arizonica 
individuals are derived from crosses between different species. In 
other words, each individual Agave arizonica was created spontaneously 
and independently from separate crossings of the putative parental 
species (M. Baker, pers. comm. 2004).
    Agave arizonica plants are rare in the wild. The likelihood is low 
that two of these plants would breed with one another because it is not 
likely that two such plants would be close enough to one another and 
bloom in the same year. Plants of a clone may produce flowers in 
synchrony, but spatially separated clones may not all bloom at the same 
time. The flowering period of Agave arizonica overlaps with that of its 
putative parents, and the same insects (bumblebees, mining bees of the 
family Halictidae, and solitary bees) visit all three agave species. 
This condition can lead to back-crosses with one of the putative 
parents. Whether Agave arizonica can maintain a separate genetic 
identity is not likely, due to low numbers, overlap of flowering period 
with the putative parents, and lack of an effective reproductive 
isolating mechanism to promote genetic stability.
    In 1999, Hodgson published a treatment for the Agave family for the 
``Flora of Arizona'' (Hodgson 1999). Agave arizonica was not recognized 
as a species in that treatment, which indicated that it should be 
referred to as Agave X arizonica, a hybrid of recent origin involving 
A. chrysantha X A. toumeyana var. bella.
    Jolly (in Riesberg 1991) has suggested protection for a hybrid 
taxon if (1) its evolution has gone past the point where it can be 
reproduced through crossing of its putative parents, (2) it is 
taxonomically distinct from its parents, and (3) it is sufficiently 
rare or imperiled. Under these criteria, F1 hybrids such as Agave 
arizonica should receive no protection.
    In summary, the plant species formerly referred to as Agave 
arizonica is now recognized as an interspecific hybrid produced 
sporadically and spontaneously by the cross of Agave chrysantha X Agave 
toumeyana var. bella. Individuals have been determined to be a hybrid 
for the following reasons: (1) They share the same chromosome number 
(2n=60) with the putative parents, indicating that there are no genetic 
barriers in place to facilitate genetic stability, (2) flowering 
periods of the putative parents overlap, (3) morphological characters 
of Agave arizonica are intermediate with those of the putative parents, 
(4) Agave arizonica only occurs where there is overlap with the 
putative parents, (5) it appears to be subfertile, producing pollen 
with low percent stainability (pollen viability is correlated with the 
ability of pollen to absorb certain chemical stains; low percent 
stainability is correlated with reduced pollen viability), (6) Agave 
arizonica can be created, ex situ, by crossing the putative parents, 
indicating that there may be no unique genetic characters associated 
with these plants, and (7) it has not, to anyone's knowledge, 
reproduced itself sexually in the field.

Previous Federal Action

    Federal Government action concerning Agave arizonica began with 
section 12 of the Act, which directed the Secretary of the Smithsonian 
Institution to prepare a report on those plants considered to be 
endangered, threatened, or extinct. This report (House Document No. 94-
51), which included Agave arizonica, was presented to Congress on 
January 9, 1975, and accepted by the Service under section 4(c)(2), now 
section 4(b)(3)(A), of the Act as a petition to list these species. The 
report, along with a statement of our intention to review the status of 
the plant taxa, was published in the Federal Register on July 1, 1975 
(40 FR 27823). On June 16, 1976, we published a proposed rule in the

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Federal Register (41 FR 24523) to determine approximately 1,700 
vascular plants to be endangered pursuant to section 4 of the Act. 
Agave arizonica was included in this proposal. On December 10, 1979, we 
withdrew all outstanding proposals not finalized within two years of 
their first publication, as required by the 1978 amendments to the Act. 
On August 26, 1980, the Service received a status report prepared by 
four researchers employed by the Museum of Northern Arizona. This 
report documented the status of, and threats to, the species. On 
December 5, 1980, we published a revised notice for plants (45 FR 
82479) and included Agave arizonica in category 1. Category 1 comprised 
taxa for which we had sufficient biological information to support 
their being listed as endangered or threatened species. We published a 
proposed rule to list Agave arizonica as an endangered species on May 
20, 1983 (48 FR 22757). No critical habitat was proposed. We received a 
total of 13 written comments on the proposal. No public hearing was 
requested or held. The final rule listing Agave arizonica as endangered 
was published on May 18, 1984 (49 FR 21055), and concurrent with the 
proposal, no critical habitat was designated.
    In 1985, a year after Agave arizonica was listed, the USDA Forest 
Service (FS) petitioned us to delist Agave arizonica because of its 
hybrid status. We sent out the work on Agave arizonica that had been 
published for peer review and solicited comments. Many of the comments 
supported delisting based on the available evidence; however, the 
Service disagreed that the available data conclusively proved that 
Agave arizonica was a hybrid. The Service believed that the results of 
the controlled crosses were important for the analysis, and those had 
not been completed at the time of the review. Therefore, on January 21, 
1987 (52 FR 2239), we announced that delisting was not warranted.

Delisting Analysis

    After a review of all information available, we are proposing to 
remove Agave arizonica from the List of Endangered and Threatened 
Plants, 50 CFR 17.12. Section 4(a)(1) of the Act and regulations (50 
CFR part 424) issued to implement the listing provisions of the Act set 
forth the procedures for adding species to or removing them from 
Federal lists. The regulations at 50 CFR 424.11(d) state that a species 
may be delisted if (1) it becomes extinct, (2) it recovers, or (3) the 
original classification data were in error. Since the time of listing, 
additional study has shown that Agave arizonica is not a distinct 
species, but consists of individuals that are the result of 
spontaneous, occasional, and continuing hybridization between two 
distinct species. In modern taxonomic practice, such groups of 
individuals are not recognized as species. We have concluded that the 
original taxonomic interpretation upon which the listing decision was 
based has not been substantiated by subsequent studies, and Agave 
arizonica does not qualify for protection because it does not fit the 
definition of a species in the Act.
    Our determination that Agave arizonica should be proposed for 
delisting is based on evidence that it is not a species and, therefore, 
does not qualify for protection under the Act, rather than on the 
control of threats. The term ``species,'' as defined in the Act, 
includes any subspecies of fish or wildlife or plants, and any distinct 
population segment of any species or vertebrate fish or wildlife which 
interbreeds when mature. Agave arizonica does not meet this definition 
because it is not known to interbreed in situ or otherwise reproduce 
itself. Hybrid origin of species is considered common within the 
flowering plants (Grant 1963). Species of hybrid origin are capable of 
reproducing themselves and maintaining a degree of genetic stability. 
Scientific evidence at this point supports the determination that Agave 
arizonica does not have these characteristics of a species. The plants 
are not known to have sexually reproduced in situ. Agave arizonica 
plants have sporadically developed in situ from the putative parents, 
but they have not been reproductively self-sustaining. Agave arizonica 
has never been found in well-developed populations or outside patches 
of its putative parents.
    We have carefully assessed the best scientific and commercial 
information available regarding the conclusion that Agave arizonica is 
a hybrid that does not qualify for protection under the Act. Based on 
this evaluation, the preferred action is to remove Agave arizonica from 
the List of Endangered and Threatened Plants, 50 CFR 17.12.

Effects of the Proposed Rule

    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to all endangered 
plants. All prohibitions of section 9(a)(2) of the Act, implemented by 
50 CFR 17.61, apply to Agave arizonica. These prohibitions, in part, 
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 remove and reduce Agave arizonica 
to possession from areas under Federal jurisdiction. For plants listed 
as endangered, the Act prohibits the malicious damage or destruction on 
areas under Federal jurisdiction and the removal, cutting, digging up, 
or damaging or destroying of such plants in knowing violation of any 
State law or regulation, including State criminal trespass law. If 
Agave arizonica is removed from the List of Endangered and Threatened 
Plants, these prohibitions would no longer apply.
    If Agave arizonica is delisted, the requirements under section 7 of 
the Act would no longer apply. Federal agencies would not be required 
to consult with us on their actions that may affect Agave arizonica.
    If delisted, Agave arizonica would continue to receive limited 
protection under Arizona's Native Plant Law, A.R.S., Chapter 7, Section 
3-901, which specifically prohibits collection except for scientific or 
educational purposes under permit.
    The 1988 amendments to the Act require that all species delisted 
due to recovery be monitored for at least five years following 
delisting. Agave arizonica is being proposed for delisting because the 
taxonomic interpretation that it is a species is no longer believed to 
be correct; Agave arizonica is a sporadically occurring hybrid, rather 
than a distinct taxon. Therefore, no monitoring period following 
delisting would be required.

Peer Review

    In accordance with our joint policy 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 such review is to ensure 
that our delisting decision is based on scientifically sound data, 
assumptions, and analyses. We will send copies of this proposed rule to 
these peer reviewers immediately following publication in the Federal 
Register. We will invite these peer reviewers to comment, during the 
public comment period, on the specific assumptions and conclusions 
regarding the proposed delisting.
    We will consider all comments and information received during the 
comment period on this proposed rule during preparation of a final 
rulemaking. Accordingly, the final

[[Page 1862]]

decision may differ from this proposed rule.

Clarity of the Rule

    Executive Order 12866 requires each agency to write regulations and 
notices that are easy to understand. We invite your comments on how to 
make this proposed rule easier to understand including answers to 
questions such as the following: (1) Are the requirements in the 
document clearly stated? (2) Does the proposed rule contain technical 
language or jargon that interferes with the clarity? (3) Does the 
format of the proposed rule (grouping and order of sections, use of 
headings, paragraphing, etc.) aid or reduce its clarity? (4) Is the 
description of the proposed rule in the SUPPLEMENTARY INFORMATION; 
section of the preamble helpful in understanding the document? (5) What 
else could we do to make the proposed rule easier to understand? Send a 
copy of any written comments about how we could make this rule easier 
to understand to: Office of Regulatory Affairs, Department of the 
Interior, Room 7229, 1849 C Street NW., Washington, DC 20240.

National Environmental Policy Act

    We have determined that an Environmental Assessment or an 
Environmental Impact Statement, as defined under the authority of the 
National Environmental Policy Act of 1969, need not be prepared in 
connection with regulations adopted pursuant to section 4(a) of the 
Act. We published a notice outlining our reasons for this determination 
in the Federal Register on October 25, 1983 (48 FR 49244).

Paperwork Reduction Act

    Office of Management and Budget (OMB) regulations at 5 CFR 1320 
implement provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et 
seq.). The OMB regulations at 5 CFR 1320.3(c) define a collection of 
information as the obtaining of information by or for an agency by 
means of identical questions posed to, or identical reporting, 
recordkeeping, or disclosure requirements imposed on, 10 or more 
persons. Furthermore, 5 CFR 1320.3(c)(4) specifies that ``ten or more 
persons'' refers to the persons to whom a collection of information is 
addressed by the agency within any 12-month period. For purposes of 
this definition, employees of the Federal Government are not included. 
The Service may not conduct or sponsor, and you are not required to 
respond to, a collection of information unless it displays a currently 
valid OMB control number.
    This rule does not include any collections of information that 
require approval by OMB under the Paperwork Reduction Act. The Agave 
arizonica is being proposed for delisting because the taxonomic 
interpretation that it is a species is no longer believed to be 
correct; Agave arizonica is a sporadically occurring hybrid, rather 
than a distinct taxon. Therefore, no monitoring period following 
delisting would be required and so we do not anticipate a need to 
request data or other information from 10 or more persons during any 
12-month period to satisfy monitoring information needs. If it becomes 
necessary to collect information from 10 or more non-Federal 
individuals, groups, or organizations per year, we will first obtain 
information collection approval from OMB.

Executive Order 13211

    On May 18, 2001, the President issued Executive Order 13211 on 
regulations that significantly affect energy supply, distribution, and 
use. Executive Order 13211 requires agencies to prepare Statements of 
Energy Effects when undertaking certain actions. As this proposed rule 
is not expected to significantly affect energy supplies, distribution, 
or use, this action is not a significant energy action and no Statement 
of Energy Effects is required.

References Cited

DeLamater, R. 1984. Natural distribution and status of Agave 
arizonica Gentry and Weber in Arizona with accompanying maps. 
Prepared for USDA Forest Service Range Management, Albuquerque, NM. 
11 pp.
DeLamater, R. and W. Hodgson. 1986. Agave arizonica: An endangered 
species, a hybrid, or does it matter? Proceedings of a California 
Native Plant Society Conference. Sacramento, CA.
Gentry, H. S. and J. H. Weber. 1970. Two New Agaves in Arizona. 
Cactus and Succulent Journal. 42(5): 223-228.
Grant, V. 1963. The Origin of Adaptations. Columbia University 
Press, New York. 606 pp.
Hodgson, W. and R. DeLamater. 1988. Agave arizonica Gentry and 
Weber; Summary of status and report on recent studies. Desert 
Botanical Gardens, Phoenix, AZ. U.S.D.I., U.S. Fish and Wildlife 
Service, Albuquerque, NM. 11 pp.
Hodgson, W. 1999. Vascular plants of Arizona: Agavaceae. Journal of 
Arizona-Nevada Academy of Science 32(1): 1-21.
Pinkava, D. J. and M. A. Baker. 1985. Chromosome and hybridization 
studies of agaves. Desert Plants. 7(2): 93-100.
Riesberg, L. H. 1991. Hybridization in rare plants: insights from 
case studies in Cercocarpus and Helianthus. In Genetics and 
conservation of rare plants. Donald A. Falk and K. E. Holsinger 
(Eds). Oxford University Press, New York. 283 pp.
Tr[auml]bold, P. A. 2001. Re-establishment--Agave arizonica. M.S. 
thesis. California State University, Fullerton, CA. 65 pp.

Authors

    The primary authors of this document are staff located at the 
Ecological Services Tucson Sub-office (see ADDRESSES section).

List of Subjects in 50 CFR Part 17

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

Proposed Regulation Promulgation

    Accordingly, we hereby 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]

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

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500; unless otherwise noted.


Sec.  17.12  [Amended]

    2. Amend Sec.  17.12(h) by removing the entry ``Agave arizonica'' 
under ``FLOWERING PLANTS'' from the List of Endangered and Threatened 
Plants.

    Dated: December 7, 2004.
Marshall Jones,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 05-442 Filed 1-10-05; 8:45 am]
BILLING CODE 4310-55-P