Rhizomes with 2 or more tubers; stipules and stipellules minute, caducous; lfls of the principal lvs 5-7, lanceolate to ovate, 4-6 cm, glabrous to short-hairy beneath; racemes dense (or looser southward), with solitary or paired brown-purple fls 10-13 mm; standard broader than long, usually retuse; fr 5-10 cm; 2n=22, and perhaps 44. Moist woods; Que. to Minn. and S.D., s. to Fla. and Tex. July, Aug. (A. tuberosa; Glycine apios)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.