Smilax \Smi"lax\, n. [L., bindweed, Gr. ???.] (Bot.) (a) A genus of perennial climbing plants, usually with a prickly woody stem; green brier, or cat brier. The rootstocks of certain species are the source of the medicine called sarsaparilla. (b) A delicate trailing plant ({Myrsiphyllum asparagoides}) much used for decoration. It is a native of the Cape of Good Hope.