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Home/Species/ Big Piney Milkvetch

Astragalus drabelliformis

Barneby

Big Piney Milkvetch

G3Vulnerable Found in 1 roadless area NatureServe Explorer →
G3VulnerableGlobal Rank
High - mediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.145919
Element CodePDFAB0F310
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single state or province
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderFabales
FamilyFabaceae
GenusAstragalus
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Taxonomic Comments
Most likely derived from A. spatulatus, perhaps by way of A. simplicifolius (K. Dueholm, pers. comm.).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2021-06-01
Change Date2021-06-01
Edition Date2021-06-01
Edition AuthorsMarriott, H. (1987), rev. W. Fertig/K. Maybury (1996), rev. C. Nordman (2021).
Threat ImpactHigh - medium
Range Extent1000-5000 square km (about 400-2000 square miles)
Number of Occurrences6 - 80
Rank Reasons
Big Piney Milkvetch ia endemic to the Green River Basin of west-central Wyoming. It is common to abundant within its very narrow range of less than 5000 square kilometers. There are about 25 occurrences, but many of these are confluent. The species is subject to medium threat impacts, including from recreational off-road vehicles. It is apparently able to colonize disturbed sites, if there are nearby intact plants which can serve as seed sources.
Range Extent Comments
Big Piney Milkvetch only occurs in the western United States, it is endemic to the Green River Basin in Sublette County, in west-central Wyoming. It is also reported from Lincoln and Sweetwater counties (SEINet 2021, WNDD 2021). Reports from Lincoln County may be misidentifications of Astragalus spatulatus (Fertig 1998, Kass 1993). All the confirmed populations of Big Piney Milkvetch are located in the Pinedale Resource Area, Rock Springs BLM.
Occurrences Comments
There have been 48 occurrences of Big Piney Milkvetch documented (WNDD 2021), but occurrences blend together in some areas. A nearly continuous population is found along the rim of Ross Butte, with smaller satellite colonies on lower terrace flats of its north and southwest slopes. Large colonies are also found on the north and south rim of Ross Ridge and at the east end of the ridge near Burma Point. At least seven small colonies occur on scattered knolls in the valley floor between Ross Butte and Ross Ridge (Fertig 1998).
Threat Impact Comments
Threats to Big Piney Milkvetch include trampling by livestock, off-road vehicle recreation impacts, and impacts from oil and gas exploration (Heidel et al. 2014, Fertig 1998, WNDD 2021). Observations suggest that Big Piney Milkvetch is able to recolonize recently disturbed quarry and roadside areas, as long as patches of undisturbed habitat persist and serve as sources of seeds (Fertig 1998).
Ecology & Habitat

Habitat

Big Piney Milkvetch occurs in sparsely vegetated cushion plant-black sagebrush (Artemisia nova) communities on rocky sandstone, limestone, or clay slopes, ridges, and roadsides (Fertig 1998, Marriott 1988). In the Ross Butte ecosystem, Big Piney milkvetch is found commonly on windswept rims of pinkish-tan to white clay sandstone or siltstone in cushion plant communities. Populations may also occur in scattered sandy-clay/gravel openings within Wyoming big sagebrush or black sagebrush grasslands on summit flats. Smaller populations also occur sporadically in cushion plant communities on lower terraces slopes or small knolls on the valley floor. Commonly associated species include Arenaria hookeri, Lomatium nuttallii, Oxytropis sericea, Phlox pungens, Erigeron compositus, Elymus lanceolatus, and Poa secunda (Fertig 1998). It occurs at 2000-2600 m elevation (SEINet 2021).
Terrestrial Habitats
Woodland - ConiferShrubland/chaparral
Other Nations (1)
United StatesN3
ProvinceRankNative
WyomingS4Yes
Threat Assessments
ThreatScopeSeverityTiming
2 - Agriculture & aquacultureLarge (31-70%)Slight or 1-10% pop. declineHigh (continuing)
2.3 - Livestock farming & ranchingLarge (31-70%)Slight or 1-10% pop. declineHigh (continuing)
3 - Energy production & miningRestricted (11-30%)Serious - moderateHigh (continuing)
3.1 - Oil & gas drillingRestricted (11-30%)Serious - moderateHigh (continuing)
6 - Human intrusions & disturbanceRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
6.1 - Recreational activitiesRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)

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Plant Characteristics
DurationPERENNIAL
Economic Value (Genus)Yes
Roadless Areas (1)
Wyoming (1)
AreaForestAcres
West Slope WindsBridger-Teton National Forest143,252
References (11)
  1. Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.
  2. Dorn, R.D. 1977. Manual of the vascular plants of Wyoming. 2 vols. Garland Publishing, Incorporated, New York. 1498 pp.
  3. Fertig, W. 1998a. Plant species of special concern of the Ross Butte Ecosystem, Sublette County, Wyoming. Wyoming Natural Diversity Database, Laramie, WY. Accessed online on August 23, 2013 at: http://www.uwyo.edu/wyndd/_files/docs/reports/wynddreports/u98fer06wyus.pdf
  4. Fertig, W., C. Refsdal, and J. Whipple. 1994. Wyoming rare plant field guide. Wyoming Rare Plant Technical Committee, Cheyenne. No pagination.
  5. Heidel, B., M. Andersen, J. Handley, and G. Beauvais. 2014. Evaluating Potential Threats to Wyoming, Threatened, Endangered and Sensitive Plant Species. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY. Online. Available: https://www.uwyo.edu/wyndd/_files/docs/reports/wynddreports/u14hei05wyus.pdf (accessed 2022).
  6. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  7. Kass, R.J. 1993. Status of bastard draba milkvetch (Astragalus drabelliformis) and Swallen mountain ricegrass (Oryzopsis swallenii) in Sublette and Lincoln counties, Wyoming. Unpublished report prepared by Intermountain Ecosystems LC. 27 pp.
  8. Kass, R.J. 1995. Status of bastard draba milkvetch (Astragalus drabelliformis) in the Upper Green River Basin, Wyoming. Unpublished report prepared for the Bur. Land Management, Rock Springs District by Intermountain Ecosystems LC. 21 pp. + appendices.
  9. Marriott, H.J. 1988. Draft habitat management plan for Threatened, Endangered, and Sensitive plant species and their habitats on the Rock Springs District, Bureau of Land Management. Unpublished report prepared by the Wyoming Natural Diversity Database, Laramie.
  10. Southwest Environmental Information Network (SEINet). 2021. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2021).
  11. Wyoming Natural Diversity Database, University of Wyoming. 2021. Astragalus drabelliformis - bastard draba milkvetch. Wyoming Field Guide. Online. Available: http://fieldguide.wyndd.org/?species=astragalus%20drabelliformis (Accessed June 2021).