Stems mostly 1–3 m, arising from a short crown; cauline lvs sessile; lfls glabrous to more often minutely puberulent beneath, mostly 3-lobed and more than 15 mm; infl ± rounded above; sep 2–3.5 mm, ± elliptic and rounded; filaments white, dilated distally, often wider than the anther, constricted at the tip; anthers usually narrowly obovoid, blunt, 0.8–1.5 mm; stigmas 0.5–2 mm, fiddlehead-curved; achenes somewhat glandular, drying dark, 3–5 mm, a third to half as wide, narrowed below to a short stipe 0.3–0.5 mm; lowest achenes much reflexed, the head of achenes therefore subglobose; 2n=84, 154. Rich woods, wet meadows, and streambanks; Lab. and Que. to Ont.,s. to s. N.C., Tenn., and Ind. June–Aug., often later than other spp. (T. polygamum)
A herb.