genus of plants of the composite family (Asteraceae), most of whose approximately 32 species occur in northwestern North America. A typical species, A. angustifolia, of Arctic Asia and America, has narrow leaves and orange-yellow flower heads 5 to 7 cm (2 to 2.5 inches) across.

One of the most important species (A. montana) is a perennial herb of northern and central European highlands. It yields an essential oil formerly used in treating bruises and sprains.