Any member of the genus Ageratina of perennials and rounded shrubs from the sunflower family, growing mainly in the warmer regions of the Americas.
Any of various plants of other genera, including Eupatorium, Asarum canadense (Canadian snakeroot), Aristolochia serpentaria (Virginia snakeroot), Eryngium cuneifolium, Plantago major, Polygala senega (Seneca snakeroot) and Rauvolfia serpentina (Indian snakeroot).