Western sweet coltsfoot, pétasite palmé

Tussilago palmata Aiton, Hort. Kew 3: 188, plate 2. 1789; Nardosmia palmata (Aiton) Hooker; Petasites arcticus A. E. Porsild; P. frigidus subsp. arcticus (A. E. Porsild) Cody; P. palmatus (Aiton) A. Gray; P. palmatus subsp. speciosus (Nuttall) Toman; P. speciosus (Nuttall) Piper

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.