1. American herb having flat-topped clusters of small white flower heads; reputedly a cause of trembles and milk sickness; sometimes placed in genus Eupatorium
   "Eupatorium rugosum was historically feared by early settlers due to its toxic effects on livestock";
   - white snakeroot, white sanicle, Ageratina altissima

Type of: herb, herbaceous plant

Part of: Ageratina, genus Ageratina

Encyclopedia: Eupatorium rugosum