Basal leaves: blades palmately to palmati-pinnately nerved, deltate or broadly cordate to reniform, 2-43 × 3.5-47 cm (bases sometimes convex-curved), irregularly palmately to palmati-pinnately lobed (primary lobes 4-14, triangular, sinuses usually less than halfway to bases, lobes subentire to sinuate-dentate, secondary lobes 0-11, entire or dentate, teeth to 44 per side), abaxial and adaxial faces glabrous or woolly to tomentose, sometimes glabrescent. Staminate heads 3-32; ray florets 2-27, corolla laminae 2.1-7.8 mm; disc floret style branches 0.4-1.4 mm, papillate or hairy. Pistillate heads 9-34; ray florets 48-89, corolla laminae 0.8-2.5 mm; disc florets: corolla lobes 0.8-2 mm, style branches 0.3-1.2 mm, papillate or hairy. Pappi (pistillate) to 15 mm. 2n = 60.

Flowering early spring. Wet marshy sites, moist woodlands; 100-1700 m; Alta., B.C., Man., Nfld. and Labr. (Labr.), N.W.T., Ont., Que., Sask., Yukon; Mich., Minn., Wash., Wis.

Petasites frigidus var. ×vitifolius often grows in association with one or both putative parents (P. frigidus var. palmatus and P. frigidus var. sagittatus).