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 is the  San Pedro cactus (Echinopsis pachanoi, syn. Trichocereus pachanoi), and Lophophora, with peyote (Lophophora williamsii) being the most psychoactive species. Several other species pertaining to other genera are also psychoactive, though not always used with a ritualistic intent.