Editing Cactus (section)

===Psychoactive agents===
[[Image:Peyote Cactus.jpg|thumb|''[[Lophophora williamsii]]'' in the wild]]
[[Image:Chavin-cactus-stone.jpg|thumb|upright|Stone carving from [[Chavín de Huantar]], dated to ''circa'' 1000 BC, showing a figure carrying what is thought to be the San Pedro cactus, [[Trichocereus macrogonus var. pachanoi|''Trichocereus macrogonus'' var. ''pachanoi'']]]]
[[File:Echinopsis pachanoi ripe fruit.jpg|thumb|''Trichocereus pachanoi'']]
A number of species of cacti have been shown to contain [[Psychoactive drug|psychoactive agents]], chemical compounds that can cause changes in mood, perception and cognition through their effects on the brain. Two species have a long history of use by the indigenous peoples of the Americas: peyote, ''[[Peyote|Lophophora williamsii]]'', in North America, and the San Pedro cactus, [[Trichocereus macrogonus var. pachanoi|''Trichocereus macrogonus'' var. ''pachanoi'']], in South America. Both contain [[mescaline]].{{sfnp|ps=none|Anderson|2001|pp=45–49}}

''L. williamsii'' is native to northern Mexico and southern Texas. Individual stems are about {{convert|2|-|6|cm|in|abbr=on|1}} high with a diameter of {{convert|4|-|11|cm|in|abbr=on}}, and may be found in clumps up to {{convert|1|m|ft|abbr=on|0}} wide.{{sfnp|ps=none|Anderson|2001|pp=397}} A large part of the stem is usually below ground. Mescaline is concentrated in the photosynthetic portion of the stem above ground. The center of the stem, which contains the growing point (the apical [[meristem]]), is sunken. Experienced collectors of peyote remove a thin slice from the top of the plant, leaving the growing point intact, thus allowing the plant to regenerate.<ref name=ZimmParf82/> Evidence indicates peyote was in use more than 5,500 years ago; dried peyote buttons presumed to be from a site on the Rio Grande, Texas, were [[Radiocarbon dating|radiocarbon dated]] to around 3780–3660 BC.<ref name=SeedDeSmBeckPoss05/> Peyote is perceived as a means of accessing the spirit world. Attempts by the [[Catholic Church|Roman Catholic church]] to suppress its use after the Spanish conquest were largely unsuccessful, and by the middle of the 20th century, peyote was more widely used than ever by indigenous peoples as far north as Canada. It is now used formally by the [[Native American Church]].{{sfnp|ps=none|Anderson|2001|pp=45–49}}

''Trichocereus macrogonus'' var. ''pachanoi'' (syn. ''Echinopsis pachanoi'') is native to Ecuador and Peru. It is very different in appearance from ''L.&nbsp;williamsii''. It has tall stems, up to {{convert|6|m|ft|abbr=on|0}} high, with a diameter of {{convert|6|-|15|cm|in|abbr=on}}, which branch from the base, giving the whole plant a shrubby or tree-like appearance.{{sfnp|ps=none|Anderson|2001|pp=277}} Archaeological evidence of the use of this cactus appears to date back to 2,000–2,300 years ago, with carvings and ceramic objects showing columnar cacti.<ref name=BussShar06/> Although church authorities under the Spanish attempted to suppress its use, this failed, as shown by the Christian element in the common name "San Pedro cactus"—[[Saint Peter]] cactus. Anderson attributes the name to the belief that just as St Peter holds the keys to heaven, the effects of the cactus allow users "to reach heaven while still on earth."{{sfnp|ps=none|Anderson|2001|pp=45–49}} It continues to be used for its psychoactive effects, both for spiritual and for healing purposes, often combined with other psychoactive agents, such as ''[[Datura ferox]]'' and tobacco.<ref name=BussShar06/> Several other species of ''Echinopsis'', including ''E. peruviana'' and ''[[Echinopsis lageniformis|E. lageniformis]]'', also contain mescaline.{{sfnp|ps=none|Anderson|2001|pp=45–49}}

{{See also|Legal status of psychoactive cactus by country}}