Lophophora diffusa
Lophophora williamsii - Peyote

Lophophora is a small genus of two species of spineless cacti native to the southwestern United States (Texas and New Mexico) through northeast Mexico south to Querétaro. The species are extremely slow growing, often taking up to thirty years to reach flowering age (at the size of about a golf ball, not including the root) in the wild. Cultivated specimens grow considerably faster, usually taking from six to ten years to go from seedling to mature flowering adult. Due to this slow growth and over-harvesting by collectors, the species are considered to be in danger of extinction in the wild.

Lophophora williamsii, commonly known as Peyote, is noted for its psychotoxic alkaloids; see Peyote for further details.

These alkaloids are are absent or only found in extremely small amounts in the other species Lophophora diffusa. Despite this, some botanists do not consider L. diffusa to be a distinct species, treating it as a variety of L. williamsii. It occurs at the south end of the range of the genus in Querétaro state, Mexico.