The Collaborative International Dictionary of English v.0.48:
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.
   [1913 Webster]
   Note: The Virginia snakeroot is Aristolochia Serpentaria;
         black snakeroot is Sanicula, esp. Sanicula
         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.
         [1913 Webster]