Distribution of Astragalus amnis-amissi (Fabaceae), a plant endemic to east-central Idaho

Astragalus amnis-amissi (Fabaceae), or Lost River milkvetch, is a plant endemic to east-central Idaho for which no published surveys have been completed in the last 18 years. A search for several previously documented populations in canyons of the southern Lemhi Range and the Lost River Range, in Butte and Custer Counties, Idaho, documented the species in 4 canyons. However, it was not relocated in an unnamed canyon in the southern Lemhi Range, indicating potential extirpation of 1 of 2 previously known populations documented on land managed by the USDI Bureau of Land Management. No new populations of A. amnis-amissi were found. Future studies on A. amnis-amissi could focus on searching for new populations, confirming the persistence of historical populations, and documenting baseline demographic data to understand potential threats to the species' long-term survival, especially climate change and recreational climbing.