Basal leaves: blades palmately nerved, orbiculate or cordate to reniform, 2-40 × 4-50 cm, margins palmately lobed (primary lobes 5-11, lanceolate to oblong or cuneate, sinuses more than halfway to bases, sometimes secondary lobes 0-13, entire or dentate, teeth to 52 per side), adaxial and abaxial faces glabrous or woolly, sometimes glabrescent. Staminate heads 4-32; ray (or pistillate) florets 5-70, corolla laminae 0 or 0.1-6.3 mm; disc floret style branches 0-1.7 mm. Pistillate heads 8-42; ray (or pistillate) florets 51-125, corolla laminae 0 or 0.1-6.3 mm; disc florets: corolla lobes 0.5-2.9 mm, style branches 0-0.8 mm, papillate or hairy. Pappi (pistillate) to 11.8 mm. 2n = 60, 61, 62.

Flowering early spring. Moist disturbed areas, stream banks, fens, swamps, roadside ditches and embankments, logging roads, moist forest soils; 10-1500 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon; Calif., Conn., Idaho, Maine, Mass., Mich., Minn., N.H., N.Y., N.Dak., Oreg., R.I., Vt., Wash., Wis.