Much branched, thinly strigose, 3-6 dm from a tuberous-thickened root; petioles mostly 2-3 cm; lfls commonly 5, narrowly obovate or oblong-obovate, 2-4 cm; spikes dense, 2-6 cm; fls blue, 15-20 mm, sessile or nearly so; cal gibbous, densely glandular, otherwise glabrous or sparsely hirsute, the tube 5-6 mm, the lowest lobe much the longest, lanceolate, 8-10 mm; fr glandular, short-beaked. Prairies and plains; Minn. to Mont., s. to Ark. and Tex. June. (Psoralea c.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.