Arnica rivularis

Arnica rivularis Greene, Pittonia 4: 163. 1900
A mica crocea Greene, Pittonia 4: 159. 1900. Not A . crocea L. 1753. Arnica crocina Greene, Torreya 1: 42. 1901.
Rootstock branched; stem 2-6 dm. high, slender, softly crisp-villous, and conspicuously glandular-granuliferous or glandularvillous above; leaves of the offsets rather long-petioled, the earliest ones with spatulate or oblanceolate and obtuse blades 4-5 cm. long, and petioles half as long, the rest with narrowly oblanceolate acute blades 8-12 cm. long, softly crispvillous on both sides', stem-leaves 3 or 4 pairs, the lower ones as those of the offsets, the upper ones lanceolate, sessile, often acuminate, entire, 4—7 cm. long; heads 1-3; peduncles 2-15 cm. long, sparingly villous and densely glandular-granuliferous; involucre 10-12 mm. high and 1520 mm. broad, villous and glandular; bracts 15-18, linear to lanceolate, acuminate; rayflowers 10-18, the ligules 12-15 mm. long, about 4 mm. wide; disk-corollas 6-7 mm. long; achenes 5 mm. long, sparingly hirsute and slightly granuliferous ; pappus-bristles 6-7 mm. long, light-brown, short-plumose.
Type locality: Powder River Mountains, Oregon. Distribution: Alaska to California. Nevada, and Alberta.