Stems coarse, somewhat woody below, reddish- brown, 2-6 dm, decumbent or ascending from a long rhizome, rooting below; lvs long-petioled, pinnately compound; lfls 5-7 (the upper 3 adjacent), narrowly oblong to elliptic, 5-10 נ1-3 cm, sharply toothed, glaucous beneath; infl leafy, few-fld; fls red-purple, 2 cm wide; bractlets narrowly lanceolate, much shorter than the acuminate sep; pet half as long as the sep; style lateral; achenes smooth, attached to the enlarged, spongy receptacle; 2n=28, 35, 42, 62-64. Swamps, bogs, and streambanks; circumboreal, s. to N.J., O., Io., and Calif. June-Aug. (Comarum p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.