Arnicas are fibrous-rooted perennials from a rhizome or root crown. The leaves are simple, opposite, or the reduced uppermost ones occasionally alternate. The flowerheads are rather large, solitary to rather numerous, in almost all cases with both ray and disk flowers. The rays are yellow or orange, relatively few and broad. The involucral bracts are herbaceous, more or less evidently in 2 series, but almost equal in length and close together. The receptacle is convex, without bracts inside. The achenes are cylindric or nearly so, 5- to 10-nerved. The pappus consists of numerous white to tawny, finely barbed to slightly feathered very fine bristles. The genus has about 30 species, of circumboreal distribution, but mostly highly developed in western N. America.
Guide to Identify Presented Species of Genus Arnica
LEAVES NARROWER, MAINLY ON STEM, THE BASAL REDUCED
A. chamissonis – Leafy Arnica Perennial, 20-100 cm tall, stems single, soft-wavy-hairy. Moist meadows.
Flowerheads yellow, 3-5 cm across, with 10-16 rays. Bracts hair-tipped.
Leaves opposite, lance-shaped, hairy, in 5-10 pairs, clasping stem, short-hairy.
