Lisa Schassberger Roe.

Report on the conservation status of Astragalus barrii, a candidate threatened species online

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Taxon Name:

Common Neune:


States Where Taxon Occurs:

Current Federal Status:

Recommended Federal Status:

Author of Report:

Original Date of Report:

Date of Most Recent Revision;

Individual to Whom Further
Information and Comments
Should be Sent:

Astragalus barrii Barneby

Barr's milk-vetch


U.S.A., Montana, South Dakota and

USFWS Notice of Review, Category 2

USFWS Notice of Review, Category 3C

Lisa Ann Schassberger

10 January 1990


J. Stephen Shelly

Montana Natural Heritage Program

State Library Building

1515 E. 6th Avenue

Helena, MT 59620


fli nr-



This is an abridged report

For the full report please contact:

The Montana Natural Heritage Program

1515 E Sixth Ave

Helena, Montana 59620




1. Classification and nomenclature 1

2. Present legal or other formal status 2

3. Description 5

4. Significance 6

5. Geographical distribution 7

6. General environment and habitat description 11

7. Population biology of the taxon 16

8. Population ecology of the taxon 26

9. Current land ownership and management responsibility. 27

10. Management practices and experience 28

11. Evidence of threats to survival 30


12. General assessment of vigor, trends, and status ... 30

13. Recommendations for listing or status change 31

14. Recommended critical habitat 32

15. Conservation/recovery recommendations 32

16. Interested parties 33


17. Sources of information 34

18. Summary of materials on file 36


19. Initial authorship 36

20. Maintenance of status report 36


21, Record of revisions 36

Literature Cited 37

Occurrence Records 39

Maps 67


1. Classification and nomenclature.

A. Species.

1. Scientific name.

a. Binomial: Astragalus barrii Barneby

b. Full bibliographic citation: Barneby,
R.C. 1956. Pugillus Astragalorum XIX:
Notes on A. sericoleucus Gray and its
immediate relatives. Amer. Midi. Nat.
55(2) : 504-507.

c. Type specimen: United States, Limestone
Butte (SE of Oelrichs) , Fall River Co.,
South Dakota, May 4, 1952, Claude A. Barr
s.n. . Type specimen deposited at
California Academy of Sciences (Barneby
1956) .

2. Pertinent synonyms: Orophaca barrii (Barneby)
Isely. Published: Isely, D. 1983. New
combinations and two new varieties in
Astragalus , Orophaca , and Oxytropis
( Leguminosae ) . Systematic Botany 8(4):420-

3. Common name: Barr's milk-vetch

4. Taxon codes: PDFAB0F150 (Montana, South Dakota
and Wyoming Natural Heritage programs) ; 5388

5. Size of genus: Astragalus barrii is one of
approximately 2,000 species in this large
genus. Roughly 550 species occur in North
America (Barneby 1964), with 47 species found
in Montana (Dorn 1984) .

B. Family classification.

1. Feunily ncime: Fabaceae.

2. Pertinent family synonym: Leguminosae.

3. Common names for the family: Pea Family.

C. Major plant group: Dicotyledoneae.


D. History of knowledge of taxon: Astragalus barrii
was described by R.C. Barneby in 1956. He was given
specimens of the plant that were originally labeled
as A. tridactylicus Gray, but which he then
determined to represent a new species. These
specimens were collected by Claude A. Barr at
Limestone Butte, Fall River County, South Dakota in
May of 1952 (Barneby 1956) .

Astragalus barrii was first collected in Montana
near Ekalaka (Carter County) , by Schunk and Schwantz
in 1943 (Barneby 1964) . This historic record was
not relocated during recent surveys.

Of the 27 currently known records for this species
in Montana, 11 records were located during a survey
by the Montana Natural Heritage Program under
contract to the Custer National Forest in 1988. In
1989, the Montana Natural Heritage Program was
contracted by the U.S. Fish and Wildlife Service to
conduct a status survey for A. barrii in Montana
(Project Agreement No. SE-5-P-2) . During surveys of
11-17 May 1989, another six populations were

E. Comments on current alternative taxonomic
treatments: Orophaca barrii (Barneby) Isely, comb,
nov. - Isely (1983) feels that Barneby's (1964)
Orophaca phalanx is not associated with any other
group of Astragalus . He based this on the
characteristics of chromosome number, large hyaline
connate stipules, unique leaves and the unilocular
and deciduous pods of the group as a whole. In
Isely 's words, "This combination of characters is
found in no other Astragalus . " Although his
systematic treatment has merit, it has not been
widely accepted.

Present legal or other formal status.

A. International.

a. Present designated or proposed legal
protection or regulation: None.

B. National.

1. United States.

a. Present designated or proposed legal
protection or regulation: Currently,
Astragalus barrii is under notice of

review for potential listing as a
threatened species under the U.S.
Endangered Species Act of 1973 (U.S.
Department of Interior 1985) .
Specifically, it is included in Category 2
(taxa for which information now in
possession of the Service indicates that
listing as a threatened or endangered
species is possibly appropriate, but for
which substantial data on biological
vulnerability and threats are not
currently known or on file to support the
immediate preparation of rules) .

The U.S. Forest Service list of sensitive
species for Region 1 (Northern Region)
currently includes Astragalus barrii (U.S.
Department of Agriculture 1988) .
Objectives and policies of the U.S. Forest
Service provide for the management and
protection of sensitive species under
sections 2670.22 and 2670.32 in the 1984
Forest Service Manual. Under these
guidelines the Forest Service is to (a)
"maintain viable populations of all native
species of plants" (2670.22), (b) "avoid
or minimize impacts to species whose
viability has been identified as a
concern" (2670.32.3) and to (c) "establish
objectives for Federal candidate species,
in cooperation with the Fish and Wildlife
Service. . .and the states" (2670.32.5).

b. Other current formal status

recommendations: Astragalus barrii is
currently listed as "very rare and local
throughout its range or found locally
(even abundantly at some of its locations)
in a restricted range" (global rank - G3)
by The Nature Conservancy.


a. Montana.

i. Present designated or proposed
legal protection or regulation:


ii. Other current formal status
recommendations: Astragalus
barrii is currently listed as

"rare m Montana" (state rank =
S3) by the Montana Natural
Heritage Program.

iii. Review of past status:

Astragalus barrii was listed as
a species of undetermined status
by the Montana Rare Plant
Project (Lesica et al. 1984).
At that time, there was not
enough information available on
the species' distribution and
abundance to assess its status
in Montana.

b. South Dakota.

i. Present designated or proposed
legal protection or regulation:


ii. Other current formal status
recommendations: Astragalus
barrii is currently listed as
"rare in South Dakota" (state
rank = S3) by the South Dakota
Natural Heritage Program (David
Ode, South Dakota Natural
Heritage Program, pers . comm.).

iii. Review of past status: None

c. Wyoming.

i. Present designated or proposed
legal protection or regulation:


ii. Other current formal status

recommendations: The Wyoming
Natural Diversity Database has
listed Astragalus barrii as
"rare in Wyoming" (state rank =
S3) (Hollis Marriott, pers.
comm. ) .

iii. Review of past status: None


A. General nontechnical description: Astragalus barrii
forms dense mats (cushions) , which rarely exceed 4
inches in height. Prostrate woody stems give rise
to numerous, leaves, each made up of 3 narrowly
elliptic leaflets. Both the stems and leaves of A.
barrii are densely covered with short, white hairs.
Iridescent bluish-purple to pinkish-purple flowers
arise on short stalks throughout the mats. In
Montana, this species blooms from late April to mid-
June, and later forms narrow, egg-shaped, one- to
few-seeded pods (adapted from Reel et ai. 1989) .

B. Technical description: Perennial, low cushion
forming plant, up to 1.5 dm. (4.5 dm.) in diameter,
with stems reduced to leafy crowns that arise from a
closely forking suf f ruticulose caudex; herbage
silvery-strigose with dolabriform hairs up to 1.4
mm. long; stipules 4-8 mm. long, glabrous dorsally;
leaves 1-4 cm. long, the 3 leaflets linear-
oblanceolate, oblanceolate or elliptic-ovate, acute
or acutish, 3-12 mm. long; peduncles slender, 7-16
mm. long, and shorter than the leaves; raceme loose,

(1) 2-4 flowered, with the fruiting axis up to 5-15
mm. long; calyx (4.6) 5.5-7.1 mm. long, the deeply
campanulate or subcylindric tube 3.6-5.1 mm. long,
the teeth (1.2) 1.5-2.4 mm. long; petals pink-
purple, the obovate-cuneate or broadly oblanceolate
banner (9.6) 10.5-16.7 mm. long; wings 9.1-13.5 mm.
long, the claws 4.1-5.5 mm.; anthers (0.45) 0.5-0.7
mm. long; pod narrowly lance-ellipsoid, 4.5-6.5 mm.
long, 1.2-1.8 mm. in diameter just above the rounded
base and tapering into a slightly incurved lance-
subulate beak about as long as the fertile portion,
obscurely triquetrous in the lower half, somewhat
flattened dorsally, the valves papery, silvery-
strigulose; ovules (7) 9-11; seeds (often only one
maturing) oblong, scarcely compressed, dull
purplish-green, smooth but not lustrous, about 2 mm.
long (adapted from Barneby 1956) .

C. Local field characters: Astragalus barrii is most
easily identified in flower, and is distinguished by
its small bluish-purple to bluish-pink flowers,
compound leaves with 3 leaflets, and mat forming

Vegetatively, Astragalus barrii is similar to A.
gilvif lorus , A. hyalinus. A. sericoleucus , and A.
aretioides , and they overlap in their geographic
distributions. Specimens of A. barrii can only be

certainly distinguished from these species when m
flower. However, in the field, A, barrii is
distinctive for its small, iridescent, bluish-
purple to bluish-pink flowers. Astragalus
gjlviflorus on the other hand, has large cream to
yellowish flowers, sometimes with purple etching,
while A. hvalinus has large white flowers with some
petals faintly lilac-tinged. Astragalus
Rericoleucus has pink-purple flowers with a paler
horizontal band, but the flowers are about one half
the size of flowers of A. barrii . The field
characteristics of A. barrii are most similar to A.
aretioides ; however, the latter has smaller flowers,
is more densely mat-forming, and is found at higher
elevations in Montana.

D. Identifying characteristics of material which is in
interstate or international commerce or trade: No
interstate or international commerce or trade is
known .

E. Photographs and line drawings: Figure 1, p. 8, is a
copy of an illustration that accompanied the
description of this species in Reel et al. (1989),
drawn by Debbie McNiel. The color slides (p. 9) are
duplicates of those taken at the sites indicated by
the three-digit occurrence numbers, Additional
slides of A. barrii and its habitat are housed at
the office of the Montana Natural Heritage Program,
Helena, Montana.

4. Significance.

A. Natural: Astragalus barrii is a regional endemic
that is known only from Southwestern South Dakota,
northeastern Wyoming and southeastern Montana. In
Montana, it is associated with the barren soils of
"gumbo clay" knolls, buttes and cliffs. In many
areas it is one of only a few species to stabilize
the soil surface.

B. Human: Astragalus barrii was first collected by a
rancher, Claude A. Barr, who also ran a small mail-
order native plant nursery. He apparently sold this
hardy species for horticultural purposes.

Astragalus barrii is also pertinent to the study and
delineation of the Orophaca phalanx, and its
placement within the genus Astragalus .

5. Geographical distribution.

A. Geographical range: A regional endemic, A. barrii
is known from 68 locations in southeastern Montana,
southwestern South Dakota, and northeastern Wyoming.

In Montana, A. barrii is currently known from sites
in Powder River (19) , Bighorn (2) , and Rosebud (6)
counties. There is also one historical record from
Carter County that has never been relocated. Within
Region 1 of the U.S. Forest Service, it has been
located on the Custer National Forest, Ashland
District (Montana) . A distribution map of A. barrii
populations in Montana is found on p. 10.

In South Dakota, this species is known from sites in
Custer (3), Fall River (3), Shannon (9), and
Pennington (6) counties; and in Wyoming from
Campbell (4) , Johnson (7) , Natrona (3) , Niobrara
(1), Sheridan (1), and Weston (3) counties.

B. Precise occurrences.

1. Populations currently known to be extant.

a. Montana: Information on populations is
listed in Occurrence Records, pp. 39-66.
Exact locations are provided on USGS
quadrangle maps, pp. 67-87.

2. Populations known or assumed extirpated,
a. Montana: None known.

3. Historically known populations where current
status is not known:

a. Montana: One location of Astragalus

barrii is documented by a voucher specimen
cited by Barneby (1964). The existing
data on this site (Ekalaka (006)) is
summarized in Occurrence Records, p. 44.
Although information on this record is
incomplete, and it was unmappable as a
specific point, it is plotted on the USGS
Ekalaka quadrangle. The location of this
historical site is also marked on Map 1, p

4. Locations not yet investigated believed likely
to support additional natural populations:

Much of the appropriate habitat for A. barrii


Astragalus barrii

Figure 1, Drawn by Debbie McNiel,

-^Hry^O*^ t,srf

Us A A'**< SoLi^g^,


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Online LibraryLisa Schassberger RoeReport on the conservation status of Astragalus barrii, a candidate threatened species → online text (page 1 of 4)