Home/Species/ Nelson's Milkvetch

Astragalus nelsonianus

Barneby

Nelson's Milkvetch

G4Apparently Secure Found in 1 roadless area NatureServe Explorer →

G4Apparently SecureGlobal Rank

LowThreat Impact

Identity

Unique IDELEMENT_GLOBAL.2.157475

Element CodePDFAB0F5V0

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryVascular Plant

Endemicendemic to a single nation

KingdomPlantae

PhylumAnthophyta

ClassDicotyledoneae

OrderFabales

FamilyFabaceae

GenusAstragalus

Synonyms

Astragalus pectinatus var. platyphyllusM.E. Jones

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.

Conservation Status

Rank Method Rank calculation - Biotics v2

Review Date2023-02-09

Change Date2023-02-09

Edition Date2023-02-09

Edition AuthorsFayette, Kim, rev. Eberly and B. Heidel (2023)

Threat ImpactLow

Range Extent5000-20,000 square km (about 2000-8000 square miles)

Number of Occurrences21 - 80

Rank Reasons

Astragalus nelsonianus is a perennial herb that occurs in the western United States. It is a regional endemic of southwestern and central Wyoming and adjoining corners of northeastern Utah and northwestern Colorado. There are over 40 extant occurrences from six counties in Colorado, Utah and Wyoming, but nearly all occurrences are in Wyoming. The species is threatened by habitat disturbance associated with oil and gas development. Trends are believed to stable.

Range Extent Comments

Astragalus nelsonianus occurs in the western United States. It is a regional endemic of southwestern and central Wyoming and adjoining corners of northeastern Utah (Daggett County) and northwestern Colorado (Moffat County). In Wyoming, it is known from the Wind River, Green River, Washakie, southern Powder River, and Great Divide Basins, Owl Creek Mountain foothills, and the Rock Springs Uplift (Carbon, Fremont, Natrona, and Sweetwater counties).

Occurrences Comments

There is one occurrence is known from Moffat County, Colorado and one in Utah. There are 40 occurrences in Wyoming.

Threat Impact Comments

Threats associated with oil and gas development are low at present and as projected for 2030. It may be affected by uranium mining (Heidel et al. 2014). It has colonized roadsides, pipeline corridors and possibly other infrastructure for energy development but it is unclear if these developments signify net impact. This species is not palatable and affected by grazing only if composition changes in highly degraded range. Invasive plant species, like Halogeton and Cheatgrass, are invading along nearby transportation corridors but there is little in occupied habitat.

Ecology & Habitat

Habitat

It is possibly restricted to seleniferous soils, in variable settings including shale bluffs and slopes, clay flats, volcanic cinders and fine sandy loam valleys or bottomlands (Barneby 1964). Vegetation is often but not always sparsely vegetated with sagebrush, juniper, and cushion plant communities (Heidel 2003). It is sometimes present in more than one topographic position and soil texture across the landscape.

Terrestrial Habitats

Grassland/herbaceousBarrens

Other Nations (1)

United StatesN4

Province	Rank	Native
Utah	S1	Yes
Wyoming	S4	Yes
Colorado	S1	Yes

Threat Assessments

Threat	Scope	Severity	Timing
3 - Energy production & mining	Restricted (11-30%)	Slight or 1-10% pop. decline	High (continuing)
3.1 - Oil & gas drilling	Restricted (11-30%)	Slight or 1-10% pop. decline	High (continuing)
8 - Invasive & other problematic species, genes & diseases	Negligible (<1%)	Serious - moderate	High (continuing)
8.1 - Invasive non-native/alien species/diseases	Negligible (<1%)	Serious - moderate	High (continuing)
8.1.1 - Unspecified species	Negligible (<1%)	Serious - moderate	High (continuing)

Plant Characteristics

DurationPERENNIAL

Economic Value (Genus)Yes

Roadless Areas (1)

Utah (1)

Area	Forest	Acres
0401001	Ashley National Forest	11,705

References (8)

Colorado Natural Heritage Program. 1998. Biological Conservation Datasystem. Colorado State University, Ft. Collins, CO.
Heidel, B. 2003. Status of Nelson's milkvetch (Astragalus nelsonianus Barneby) in Wyoming. Unpublished report to the Bureau of Land Management. Wyoming Natural Diversity Database, Laramie.
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).
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.
Rosenfeld, I. and O.A. Beath. 1964. Selenium - Geobotany,Biochemistry, Toxicity, and Nutrition. Academic Press, New York, NY.
Utah Natural Heritage Program. May 1998. Element Occurrence Record Database, National Park subset. Salt Lake City, UT.
Weber, W.A., and R.C. Wittmann. 1996a. Colorado flora: Eastern slope. Revised edition. Univ. Press of Colorado, Niwot, Colorado. 524 pp.
Wyoming Natural Diversity Database. 1998. University of Wyoming, Laramie, WY.

Astragalus nelsonianus

Habitat

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