Distribution: Chiefly east of the Cascades, British Columbia to California, east to Wyoming.
Habitat: Open, often rather dry places, but usually vernally moist, in the foothills and at moderate elevations in the mountains.
Flowers: May - July
Conservation Status: Not of concern
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.