Much branched, densely white-sericeous throughout, eglandular, 3-6 dm, rhizomatous; petioles 1-3+ cm; lfls 3 or 5, narrowly elliptic to oblanceolate or narrowly ovate, 2-5 cm; spikes 2-8 cm; interrupted, with 1-5 fascicles of dark blue, sessile fls 8-10 mm; cal-tube 2-3 mm; lowest cal-lobe lance-linear, 4.5-7 mm, twice as long as the upper 4; fr densely silky; 2n=22. Dry prairies and plains; Minn. and Wis. to Mo., w. to Sask., Mont., and N.M. June-Aug. (Psoralea a.; Psoralidium a.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.