Precocious Milkvetch

Perennial, Herbs, Stems woody below, or from woody crown or caudex, Taproot present, Nodules present, Stems very short, acaulescent or subacaulescent, Stems erect or ascending, Stems less than 1 m tall, Stems solid, Stems or young twigs sparsely to densely hairy, Stems silvery, canescent, tomentose, cobwebby, or wooly, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules membranous or chartaceous, Stipules persistent, Stipules clasping stem at the base, Stipules connate to each other, forming a tuber or sheath, Leaves compound, Leaves palmately 2-3 foliate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 3, Leaves hairy on one or both surfaces, Flowers solitary in axils, or appearing solitary, Flowers in axillary clusters or few-floweredracemes, 2-6 flowers, Inflorescence axillary, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals white, Petals ochroleucous, cream colored, Banner petal narrow or oblanceolate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel petals auriculate, spurred, or gibbous, Keel tips obtuse or rounded, not beaked, Stamens 9-10, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style persistent in fruit, Fruit a legume, Fruit unilocular, Fruit freely dehiscent, Fruit oblong or ellipsoidal, Fruit rugose wrinkled or reticulate, Fruit fleshy, Fruit coriaceous or becoming woody, Fruit enclosed in calyx, Fruit beaked, Fruit hairy, Fruit 3-10 seeded, Fruit 11-many seeded, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.

Astragalus proimanthus is a species of flowering plant in the legume family known by the common name precocious milkvetch. It is a narrow endemic, occurring in an area of less than 320 acres near the town of McKinnon in southwestern Sweetwater County, Wyoming. It has four known populations, including one large population of more than 20,000 individuals, and is classified by NatureServe as G1 (critically imperiled) "because of extreme rarity".