The peyote is a small, spineless cactus which contains psychoactive alkaloids, particularly mescaline. Peyote is a Spanish word derived from the Nahuatl peyōtl, meaning "caterpillar cocoon", from a root peyōni, "to glisten". Peyote is native to Mexico and southwestern Texas. It is found primarily in the Sierra Madre Occidental, the Chihuahuan Desert and in the states of Nayarit, Coahuila, Nuevo León, Tamaulipas, and San Luis Potosí among scrub. It flowers from March to May, and sometimes as late as September. The flowers are pink, with thigmotactic anthers.

Many cacti are known to be psychoactive, containing phenethylamine alkaloids such as mescaline. However, the two main ritualistic (folkloric) genera are Echinopsis, of which the most psychoactive species occur in the San Pedro cactus group, and Lophophora, with peyote being the most psychoactive species. Several other species pertaining to other genera are also psychoactive, though not always used with a ritualistic intent.