Stems 2-10 dm from an often tuberous-thickened, otherwise fibrous-rooted base, subequally quadrangular and evidently winged, usually ±bristly at the nodes, otherwise bristly to glabrous; lvs ovate to lance-ovate, 2-7 cm, usually a third to half as wide, sometimes bristly on one or both sides; hypanthium smooth or bristly, 7-10 mm at maturity, the neck mostly shorter than the body; sep narrow, acute or acuminate, 2-4 mm; pet rose-lavender, 15-20 mm, often bristly on the back; anthers 5-7 mm; 2n=22, 44. Moist, open places; N.S. to Wis., s. to Fla. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.