The Collaborative International Dictionary of English v.0.48:

Poke \Poke\, n. (Bot.)
   A large North American herb of the genus Phytolacca
   (Phytolacca decandra), bearing dark purple juicy berries;
   -- called also garget, pigeon berry, pocan, and
   pokeweed. The root and berries have emetic and purgative
   properties, and are used in medicine. The young shoots are
   sometimes eaten as a substitute for asparagus, and the
   berries are said to be used in Europe to color wine.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pokeweed \Poke"weed`\, n. (Bot.)
   See Poke, the plant.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pokeweed
    n 1: perennial of the genus Phytolacca