Stem erect, 5-12 dm, glabrous or nearly so below the much-branched infl; stipules lance-subulate, 5-8 mm; lfls thin, ovate, glabrous, glaucous beneath, the terminal one 4-8 cm, half to three-fourths as wide; fls 8-10 mm, deep rose or purple, on pedicels 10-20 mm; cal 3.5-5 mm; stipe 3.5-6.5 mm; articles 2-5, 4.5-8 mm, glabrous or nearly so on the upper suture, the lower suture abruptly curved near the middle. Dry upland woods; s. N. Y. to Ind. and Mo., s. to Fla. and Tex. July, Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.