Stems glabrous or nearly so, decumbent, 1-5 dm, scattered on a freely branching, subterranean caudex; stipules connate; lfls mostly 15-25, narrowly oblong to oval, 1-2 cm, sparsely hairy on both sides or glabrous above; racemes long-peduncled, 2-4 cm, loosely few-fld, elongating with maturity; fls nodding, purple or purplish, 10-13 mm; cal-tube broad, 2 mm, the triangular lobes 1 mm; keel slightly to evidently surpassing the wings, equaling or a little shorter than the standard; fr pendulous, lance- oblong, 8-13 mm, ±falcate, pubescent with mixed black and white hairs, evidently trigonous, deeply sulcate on the lower side, the suture also intruded to form a partial partition; stipe 2-4 mm; 2n=16, 32+. Circumboreal, extending s. on gravelly river-banks and lake-shores to Nf., Me., Vt., and Wis., and in the w. to Colo. June-Aug. Typical var. alpinus, with the cal and fr densely pubescent with loosely ascending hairs ca 0.5 mm, occurs in Bayfield Co., Wis., and is widespread far beyond our range. (Atelophragma a.) Var. brunetianus Fernald, with the hairs of the pod shorter (0.2-0.4 mm) and usually appressed, occurs from e. Vt. to Que. and Nf. (A. labradoricus)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.