Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to Alberta, Montana, and Wyoming.
Habitat: From low elevation prairies and grasslands to coniferous forest openings at middle elevations.
Growth Duration: Perennial
Conservation Status: Not of concern
Pollination: Apomixis, bumblebees, butterflies
Perennial from slender rhizomes, the slender stems 2-6 dm. tall
Basal leaves petiolate, the blades lanceolate, 3-12 cm. long and 1-2.5 cm. wide; cauline leaves 2-4 pair, the lower ones with short petioles, reduced upward.
Heads few; involucres 10-15 mm high, the bracts narrow, tapering from the base, pointed; disk corollas with stalked glands; pappus white
The similar Arnica fulgens has long, woolly brown hairs in the axils of the lower leaves; A sororia usually has no axillary hairs; if any are present, they are white.