Arnica chamissonis Less.
ssp. foliosa Nutt
Single stemmed perennial from 8-24 inches tall with 5-10 pairs of heart shaped lower leaves, 1-3 inches long and opposite. It has a sunflower like, yellow flower of yellow about 2 inches across. Blooms in the latter part of May through July. It grows in either acid or alkaline soil and grows well in sun or partial shade. Found mostly in meadows and wet places, from the foothills to middle or upper level elevations in the mountains. Reported by Nuttall on the alluvial flats of the Colorado of the West, (the Snake) particularly near the Bear River (southeastern Idaho). An example of Nuttall's Chamisso Arnica plant is at the British Museum.
WARNING: Arnica should be only used with extreme care. Arnica may cause contact dermatitis (inflammation of the skin, especially in allergy-prone persons) when used externally, and complete collapse when taken internally. Therefore, Arnica is subject to legal restrictions in many countries.
Arnica is restricted for external use only in the USA. Externally Arnica may be used in liniments or creams for for sunburn, superficial and limited burns, bruises, sprains, swollen feet.dislocations, sprains, bruises, chilblains and varicose ulcers.