Broadleaf Arnica Arnica latifolia Aster family (Asteraceae)
There are a number of yellow Arnicas found on in the Rockies and they often grow in the same general vicinity. A careful scrutiny will show you the sometimes small, sometimes large differences. You can distinguish A. latifolia from the other species by observing its broad leaves attached close to the stem, a white (appearing barbed in a hand lens), and 5-9 pairs of leaves. "" is Latin for "broad leaf."
Leafy plant to 16" tall, sparsely hairy and often slightly tacky or sticky. Broad or leaves in pairs, or nearly so, the middle leaves the longest at 2-3", truncated or at the base. Stems erect and having 1-5 hairy and flower heads up to 3/4" high, with 8-12 yellow , and a white, barbed .