The Collaborative International Dictionary of English v.0.48:

Serpentaria \Ser`pen*ta"ri*a\, a.[L. (sc. herba), fr. serpens
   serpent.] (Med.)
   The fibrous aromatic root of the Virginia snakeroot
   (Aristolochia Serpentaria).
   [1913 Webster]

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]

WordNet (r) 3.0 (2006):

Aristolochia serpentaria
    n 1: birthwort of the eastern United States woodlands [syn:
         Virginia snakeroot, Virginia serpentaria, Virginia
         serpentary, Aristolochia serpentaria]