Rather stout, simple, 2—5 feet high. Leaves thin, all more or less petioled and dentate, deltoid-lanceolate or the lower triangular-hastate or deltoid-cordate, the uppermost lanceolate, with cuneate base. Heads of flowers about ½ an inch high, numerous in a flat open cyme; involucre campanulate; rays 8—12, bright yellow, oblong-linear, ¼—⅓ of an inch long. In wet ground and along the borders of streams and wet slopes at 5000 to 6000 feet elevation throughout the Rockies; at much lower altitudes in the Selkirks where it is a very abundant plant; flowering in June and early July. [Sidenote: =Petasites palmata= (Ait.) A. Gray. _Palmate-leaved Coltsfoot._] Scape slender and scaly, 6—24 inches high. Leaves nearly orbicular in outline, 3—12 inches broad, deeply 7—11-cleft to much beyond the middle, green and smooth above, densely white-woolly beneath, at least when young; the lobes oblong to obovate-acute, often somewhat wedge-shaped, sharply dentate or cut. Heads mostly diœcious, numerous, corymbose, ⅓—½ an inch broad; flowers usually white, fragrant, the marginal ones of the pistillate heads with narrow pinkish or white rays about ¼ of an inch long; cottony in fruit. In wet places and along streams at the lower altitudes throughout the Rockies; flowering in May and early June before the leaves appear. [Sidenote: =Petasites sagittata= (Pursh.) A. Gray. _Arrow-leaved Coltsfoot._] Scape slender and scaly, 6—12 inches high. Leaves deltoid-ovate or reniform-ovate, persistently white-tomentose beneath; smooth or nearly so above, 4—10 inches long, thin, margins sinuate-dentate, not cleft or lobed. Heads diœcious, loosely corymbose, involucre campanulate, ⅓ of an inch high; flowers nearly white, the marginal ones of the pistillate heads with white rays. In similar situations to the preceding; in wet places and along streams at the lower altitudes throughout the Rockies; readily distinguished by the shape of its leaves; flowering in May and early June. [Sidenote: =Petasites frigida= (L.) Fries. _Arctic Coltsfoot._] Scape very, scaly, 3—10 inches high. Leaves thin, hastate-reniform to triangular-ovate, 1—4 inches long, irregularly and angulately lobed and incised, smooth and green above, persistently white-woolly beneath, the lobes entire or few-toothed. Heads usually few, ½ an inch or more high in a capitate corymb; involucre short, campanulate; flowers nearly white and fragrant, the marginal ones of the pistillate heads with white or pinkish rays ¼ of an inch or more long. In shaded wet places and along alpine brooks at the high altitudes throughout the region; flowering during June and July with the expanding leaves. [Sidenote: =Achillea lanulosa= Nutt. _Yarrow._]