Erect, branched above, to 12 dm; lvs several pairs, ovate or ovate-oblong, acuminate, glabrous, the lower 1-2 dm, on petioles to 1 cm, the upper progressively smaller and the uppermost commonly sessile; panicles 1-3 dm, divergently branched, often compound with branches from the uppermost lf-axils; fls all paired at the minutely bracteate nodes of the infl; cal 2.5-4 mm at anthesis, weakly bilabiate, 8 mm in fr; cor 12-15 mm, the lower lobe oblong, nearly as long as the tube; stamens 2; 2n=50. Rich woods; Que. to Mich. and s. Wis., s. to Fla. and Ark. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.