Peyote is a type of hallucinogen-yielding cactus native to the southwestern United States and northern Mexico. It has been used by Native Americans for centuries in religious ceremonies and for medicinal purposes. The active ingredient in PEYOTE is mescaline, which produces psychedelic effects when ingested. PEYOTE is also known as Lophophora williamsii, and its scientific name is derived from the Greek words for 'CROWN' and 'DIVINE'.