EUPATORIUM, a numerous genus of plants of the family Compositae, comprising more than Soo species, nearly all Ameri can and found chiefly in tropical South America, the West Indies and Mexico. They are mostly perennial herbs, a few are annuals, and many tropical species are shrubby or tree-like. The leaves are usually opposite and the flowers are borne in rayless heads disposed usually in flat-topped clusters. Of the few Old World species, one, E. cannabinum, the hemp-agrimony, occurs in Great Britain. Upwards of 6o species are found in the United States and Canada, widely distributed but mostly in the eastern, southern and south-western States, very few occurring on the Pacific coast. Representative North American species are E. per f oliatum, bone- . set (q.v.); E. purpureuin, Joe-Pye weed; E. urticaefolium, white snake-root ; and E. coelestinum, mist-flower. Various tropical forms are in greenhouse cultivation and several hardy species are grown as border plants.