smilax, common name for a florists' plant of two separate genera (Asparagus and Smilax), both of the family Liliaceae (lily family, although some botanists recognize smilax as a separate family, the Similacaceae). The greenbriers, prickly vines often weedy in North America, belong to the same genus (Smilax) as the plants yielding sarsaparilla. Both genera are classified in the division Magnoliophyta, class Liliopsida, order Liliales, family Liliaceae.