The Pacific Northwest and the Rocky Mountain states, plus north California and north Nevada
Woodland, mountain meadows, moist areas
Opposite, ovate, with small teeth along the edges, up to 4 inches long
The leaves of arnica latifolia help distinguish this species from similar members of this genus, being broadly ovate, toothed along the edge and sparsely covered by thin, straggly hairs. Plants have 2 to 6 pairs of leaves along the stem, and between 1 and 5 flowers (occasionally up to 9). Basal leaves grow early in the season but are usually withered by flowering.
Each flower is formed of 8 to 15 yellow ray florets, with 2 notches at the tip, and a center of between 20 and 90 tiny yellow disc florets. Underneath are 8 to 20 hairy green phyllaries, with pointed, reddish tips. The green stems are also hairy. The plant spreads readily, via underground stems.