Rhizomatous perennial 4-8 dm; lvs ovate, 1.5-3 cm, entire or nearly so, on petioles half as long; infl rounded or pyramidal, 5-15 cm wide, the ultimate cymules crowded; smaller bracts usually reddish-tinged; cal 2.5 mm, the lobes a fourth as long as the tube; cor purple-red to pale pink, 6-8 mm; 2n=30, 32. Native of Eurasia, intr. in disturbed sites, especially in calcareous soil, from N.S. to Ont., s. to N.C. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.