What is "eupatorium ageratoides"

Snakeroot \Snake"root`\, n. (Bot.) Any one of several plants of different genera and species, most of which are (or were formerly) reputed to be efficacious as remedies for the bites of serpents; also, the roots of any of these.

Note: The Virginia snakeroot is Aristolochia Serpentaria; black snakeroot is Sanicula, esp. S. Marilandica, also Cimicifuga racemosa; Seneca snakeroot is Polygala Senega; button snakeroot is Liatris, also Eryngium; white snakeroot is Eupatorium ageratoides. The name is also applied to some others besides these.