A plant genus of the family asteraceae. The dried flower heads of arnica montana are used externally as a counterirritant and tincture for sprains and bruises, either as crude extract or in homeopathic dilution (homeopathy). arnica contains volatile oils (oils, volatile), arnicin, arnisterol, flavonoids; tannins; and resin. The common name of Wolf's Bane is similar to the common name for aconitum.