The sarsaparilla plants (Spanish zarza, “bramble,” and parrilla, “little vine”) are native to the southern and western coasts of Mexico to Peru. They are large, perennial, climbing or trailing vines with short, thick, underground stems producing many prickly, angular, aboveground stems. These are supported by tendrils springing from the bases of large, alternate, stalked leaves.

The commercial species providing sarsaparilla are principally Smilax aristolochiaefolia, S. regelii, and S. febrifuga, respectively known as Mexican, Honduran, and Ecuadorian sarsaparillas. Other commercial Smilax species include Ecuadorian (Guayaquil) and Central American (Jamaican or Guatemalan). After drying in the sun, the roots are gathered loosely into bundles or bound tightly into cylinders, depending on the place of origin, and then exported.

Several sterols and a crystalline glycoside, sarsaponin, which yields sarsapogenin on hydrolysis, have been isolated from the root. Sarsapogenin is related to steroids such as progesterone and is used in their synthesis.

In North America the strongly aromatic roots of the wild sarsaparilla (Aralia nudicaulis) and false or bristly sarsaparilla (Aralia hispida) are sometimes substituted for true sarsaparilla.