Arnica trinervata

Arnica trinervata Rydberg
Arnica stricla Greene, Ottawa Nat. 23: 214. 1910. Not A. slricta A. Nels. 1901.
Rootstock short, horizontal; stem 2-6 dm. high, striate, viscidvillous and glandularpuberulent, densely so in the inflorescence; basal leaves several, oblong-oblanceolate to oval or spatulate, obtuse, 5-7-ribbed (three of the ribs prominent), tapering below into a winged petiole, 5-12 cm. long, 1-2.5 cm. wide, glandular-puberulent and somewhat viscidvillous; stemleaves 3 or 4 pairs, the lowest pair similar to the basal leaves but with broader petioles, the rest lanceolate or linear, sessile; heads 1-11; peduncles 5-15 cm. long; involucre hemispheric, about 15 mm. high, 15-25 mm. broad, viscid-villous and glandular-puberulent; bracts 15-20, linear or linear-lanceolate, acute; ray-flowers 8-15, the ligules orange, 12-20 mm. long, 5-6 mm. wide; disk-corollas 8 mm. long; achenes 5 mm. long, hirsute; pappus-bristles white, 7 mm. long, barbellate.
Type locality: Between the Columbia and Kettle Rivers, west of Cascade, British Columbia. Distribution: British Columbia to Idaho and California.