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Mountain Arnica, Broadleaf Arnica: Arnica latifolia - Leaves larger, usually 1.5-8 cm broad, often noticeably toothed. The 1-3 flower heads are larger and wider than those of the next species, with the involucres measuring from 10-18 mm high. Larger plants from 10-60 cm high, found in moist woods, medows, and moist open places in the mountains, more typically at lower elevations than the next species.
Slender Arnica: Arnica gracilis (A. latifolia var. gracilis) - Leaves small, usually less than 2.5 cm wide. The 3-9 narrow heads are small, the involucre measuring 7-13 mm hgih. Small tufted plants from 10-30 cm high, found on rocky to cinder slopes that are more exposed, and usually higher than A latifolia.
