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Astragalus adanus

A. Nels.

Boise Milkvetch

G2Imperiled Found in 1 roadless area NatureServe Explorer →
G2ImperiledGlobal Rank
High - mediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.145261
Element CodePDFAB0F050
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.
Conservation Status
Rank MethodLegacy Rank calculation - Biotics v1
Review Date2020-01-13
Change Date2020-01-13
Edition Date2020-01-13
Edition AuthorsBroaddus, Lynn (1991), rev. A. Tomaino (2020)
Threat ImpactHigh - medium
Range Extent250-1000 square km (about 100-400 square miles)
Number of Occurrences21 - 80
Rank Reasons
Known only from around and within the north edge of the Snake River Plain, Idaho. Threats include residential development, invasive plants, grazing, and recreation.
Range Extent Comments
Known only from southwestern Idaho, around and within the north edge of the Snake River Plain (Hitchcock and Cronquist 2018; Barneby 1989). Mistakenly attributed to Utah (Barneby 1989).
Occurrences Comments
Twenty-two sites listed in Barneby (1964), but he states that it is not rare in southwestern Idaho in certain river valleys.
Threat Impact Comments
Threats include residential development, invasive plants, grazing, and recreation (Halford 2013).
Ecology & Habitat

Habitat

Occurs on brushy slopes, terraces and benches along canyons or along dry flats and gently rolling hill country among sagebrush in alluvial clays and gravels of both granitic and basaltic origin (Barneby, 1964). Habitat described as dry hillsides, often with sagebrush (Hitchcock and Cronquist 2018). Sometimes in Douglas fir or submontane brush communities (Barneby 1989). The habitat of this species consists of areas which have primarily been mapped as Central Rocky Mountain Lower Montane, Foothill & Valley Grassland (G273), Intermountain Montane Sagebrush Steppe (G304), and it may also persist in areas mapped as Western Interior Ruderal Grassland & Shrubland (G624), and Great Basin-Intermountain Ruderal Dry Shrubland & Grassland (G600) at the group level of the US National Vegetation Classification (NatureServe 2025).
Terrestrial Habitats
Shrubland/chaparralGrassland/herbaceous
Other Nations (1)
United StatesN2
ProvinceRankNative
IdahoS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentRestricted - smallExtreme or 71-100% pop. decline—
1.1 - Housing & urban areasRestricted - smallExtreme or 71-100% pop. decline—
2 - Agriculture & aquacultureLarge (31-70%)Moderate - slight—
2.3 - Livestock farming & ranchingLarge (31-70%)Moderate - slight—
6 - Human intrusions & disturbanceSmall (1-10%)Slight or 1-10% pop. decline—
6.1 - Recreational activitiesSmall (1-10%)Slight or 1-10% pop. decline—
8 - Invasive & other problematic species, genes & diseasesPervasive - restrictedModerate or 11-30% pop. decline—
8.1 - Invasive non-native/alien species/diseasesPervasive - restrictedModerate or 11-30% pop. decline—

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Plant Characteristics
Economic Value (Genus)Yes
Roadless Areas (1)
Idaho (1)
AreaForestAcres
Peace RockBoise National Forest191,734
References (7)
  1. Barneby, R.C. 1964. Atlas of North American Astragalus. 2 Vols. New York Botanical Garden, Bronx, New York. 1188 pp.
  2. Barneby, R.C. 1989. Fabales. In A. Cronquist, A.H. Holmgren, N.H. Holmgren, J.L. Reveal, and P.K. Holmgren (eds.). Intermountain flora: Vascular plants of the Intermountain West, U.S.A. Vol. 3, Part B. New York Botanical Garden, Bronx. 279 pp.
  3. Halford, A.S. 2013. Species account for Astragalus adanus. Idaho Native Plant Society and Idaho Natural Heritage Program.
  4. Hitchcock, C.L., and A. Cronquist. 2018. Flora of the Pacific Northwest: An illustrated manual. Edited by D.E. Giblin, B. S. Legler, P.F. Zika, and R. G. Olmstead. 2nd edition. Univ. Washington Press, Seattle. xiii + 822 pp.
  5. Idaho Department of Fish and Game. 2020. Idaho Fish and Wildlife Information System. Online. Available: https://idfg.idaho.gov/species/taxa/list (accessed 2020).
  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. NatureServe. 2025. Ecosystems of the Conterminous US and Adjacent Areas, Version 1.0. NatureServe, Arlington, Virginia. Online. Available: https://natureserve.maps.arcgis.com/home/item.html?id=66c13612635d4ee9bd4d6500cf462e7f (Accessed 2025).