Arnica is a perennial, herbaceous plant growing 20 to 50 cm high. Leaves are hairy, slightly toothed, and form a basal rosette. The daisy-like flowers are usually egg-yolk yellow to orange-yellow, 6 to 8 cm in diameter on a flower stalk 1 to 2 feet tall. It blooms Aug-Oct. The rhizome is dark brown, cylindrical, usually curved, and bears brittle wiry rootlets on the underside. Introduced from Europe, it thrives in well-drained, humus-rich, sandy, acid soil in a sunny position.