Shrub-like perennial from a usually branched caudex. Herbage sparsely strigose. Stems erect, 20–70 cm, hollow at the base. Leaves with 15 to 23 narrowly elliptic leaflets, 1–2 cm long with rounded tips; stipules lanceolate, 3–6 mm long. Inflorescence dense with 20 to 80 nodding flowers. Flowers purple (white); sepals 1–4 mm long; calyx black- and/or white-hairy; banner becoming reflexed 10–15 mm long; keel 9–13 mm long. Legume 10–15 mm long, glabrous or strigose, linear with 2 grooves beneath, pendulous with a stipe 2–4 mm long
(Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Our plants are variety
bisulcatus.