Perennial from a branched caudex. Herbage sparsely to densely strigose. Stems prostrate to ascending, 5–40 cm. Leaves with 13 to 21 narrowly oblong leaflets, 5–20 mm long with rounded tips; stipules lanceolate, 3–8 mm long, distinct. Inflorescence shorter than the leaves, crowded, of 5 to 20 spreading to ascending flowers. Flowers purple or white and purple-tipped; calyx black- and/or white-strigose; sepals 2–4 mm long; banner 22–30 mm long, moderately reflexed; keel 14–20 mm long. Legume spreading, globose, glabrous, 13–20 mm long, fleshy, becoming hard, leathery (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
Montana plants are varieties crassicarpus
(E.H. Kelso) Barneby.