A. Gray
Identity
Unique IDELEMENT_GLOBAL.2.143087
Element CodePDFAB0F4N0
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicendemic to a single nation
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderFabales
FamilyFabaceae
GenusAstragalus
Other Common NamesLemmon's milkvetch (EN)
Concept ReferenceKartesz, 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 Date2025-02-24
Change Date2010-02-25
Edition Date2025-02-24
Edition AuthorsBroaddus, Lynn, rev. A. Tomaino and R. Bittman (2010), rev. N. Ventrella (2025)
Threat ImpactHigh
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences21 - 80
Rank ReasonsAstragalus lemmonii is a perennial forb occurring in Great Basin scrub in seasonal wetlands, alkali meadows, and flats along streams and lakeshores of the western United States in northeastern California, south-central Oregon, and Nevada on the eastern side of the Cascade-Sierrian axis. The report from Nevada is from a single, likely historical herbarium collection from Washoe County, which needs verification. There are an estimated 23 occurrences of this species, which are threatened by grazing and trampling by livestock, off-road vehicles, invasive species, development, rights-of-way maintenance, climate change and drought, and (potentially) wildfire. The largest known population (of over 41,000 plants) occurs in Oregon in the Fremont-Winema National Forest in a relatively small area of less than fourteen square kilometers.
Range Extent CommentsAstragalus lemmonii occurs in the western United States in northeastern California, south-central Oregon, and in Washoe County, Nevada on the eastern side of the Cascade-Sierrian axis (Dean 2022, Calflora 2025, NatureServe 2025, OSU 2025). Range extent was estimated using herbarium specimens, photo-based observations, and California Natural Diversity Database occurrence data (RARECAT 2024, CNDDB 2025, CPNWH 2025, iNaturalist 2025, SEINet 2025).
Occurrences CommentsBy applying a 1 km separation distance to herbarium specimens, photo-based observations, and California Natural Diversity Database occurrence data, it is estimated that there are 23 occurrences rangewide (RARECAT 2024, CNDDB 2025, CPNWH 2025, iNaturalist 2025, SEINet 2025). In Nevada, the single known occurrence from Washoe County may be historical and has not been observed since before 2000 (though the exact date is unknown) (NatureServe 2025).
Threat Impact CommentsAstragalus lemmonii is threatened by grazing and trampling by livestock, off-road vehicles, invasive species, development, and rights-of-way maintenance (CNDDB 2025). One occurrence in California is threatened by development and fencing associated with a fish hatchery, and in Nevada, the single occurrence is threatened by expansion of residential development (NNHP 2001, CNDDB 2025). This species occupies mesic habitats in Great Basin shrub, often along creeks, lake margins, and wet places in meadows, and it is susceptible to changes to hydrology or water availability. Climate change and associated drought conditions are a concern for Astragalus lemmonii (ONHP 2013, Dean 2022). In Oregon, plants occur in seasonal wetlands in drier eastern regions of the state, where this species is considered highly vulnerable to changes to precipitation regimes (ONHP 2013). Wildfire and associated weed invasion into habitat following fire is a threat to the closely-related Astragalus mulfordiae, another rare perennial species that does not reproduce clonally, and could also be a threat to A. lemmonii (Mancuso 1999, Dean 2022).