Hallucinogenic cactus is a term used to describe two species of cacti, PEYOTE (Lophophora williamsii) and MESCAL (Lophophora diffusa), which contain psychoactive alkaloids that can cause hallucinations when ingested. PEYOTE is native to the southwestern United States and northern Mexico, while MESCAL is native to central and northern Mexico. Both cacti have been used for centuries by indigenous cultures for spiritual and medicinal purposes.