The Collaborative International Dictionary of English v.0.48:

Bull brier \Bull" bri`er\ (Bot.)
   A species of Smilax (Smilax Pseudo-China) growing from New
   Jersey to the Gulf of Mexico, which has very large tuberous
   and farinaceous rootstocks, formerly used by the Indians for
   a sort of bread, and by the negroes as an ingredient in
   making beer; -- called also bamboo brier and China brier.
   [1913 Webster]