1d. Petasites frigidus (Linnaeus) Fries var. x_vitifolius (Greene) Cherniawsky, Canad. J. Bot. 76: 2072. 1999.
Pétasite à feuilles de vigne
Petasites vitifolius Greene, Leafl. Bot. Observ. Crit. 1: 180. 1906; P. nivalis Greene subsp. vitifolius (Greene) J. Toman; P. trigonophyllus Greene; P. warrenii H. St. John
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).
Bogle, A. L. 1968. Evidence for the hybrid origin of Petasites warrenii and P. vitifolius. Rhodora 70: 533–551.