Name: Psilocybe mexicana
Author: R. Heim
Citation: Revue Mycol., Paris 22: 77 (1957)
Holotype HUA, Guzmán 29561-B
On soil in subtropical zone: Colombia
Psilocybe mexicana, first described by R. Heim in 1957, can be differentiated from closely related species by the presence of hyaline pleurocystidia and cheilocystida and of rhomboid or subrhomboid spores more than eight microns in length, by a lack of annulus, and by its propensity to stain blue or to fade to blackish when dried or damaged (Guzman 1983 78). At a very basic level of identification, hallucinogenic Psilocybe species can be distinguished from nonhallucinogenic Psilocybe species by their tendency in almost all cases to oxidize blue, by their farinaceous odor and taste (Guzman 2008 408), and by the fact that they grow only in acid media (Guzman 1983 26). P. mexicana is found in the states of subtropical Mexico and Guatemala (Stamets 129-130) at elevations between 1000 and 2000 meters (Guzman 1983 30) and exhibits seasonality, typically fruiting between June and September. The species occurs in meadows, often in horse pastures, in soils rich in manure, or along field-deciduous forest interfaces and can exhibit both solitary and gregarious habits (Stamets 129). Although the species is not thought to engage in mycorrhizal relationships with trees, studies have reported a higher probability of the species’ occurrence in meadows with the following tree species present: sweetgum (Liquidamambar styraciflua), oak (Quercus sp.), and alders (Alnus sp.) and in river valleys and pastures bordered by sycamore (Platanus lindeniana) (Stamets 130).
Psilocybe mexicana is a moderately potent hallucinogen due to the presence of both psilocybin (4-phosphoryloxy-N,N-dimethyltryptamine) and its biologically active form, psilocin (4-hydroxy-N,N-dimethyltryptamine), in the species’ fruiting bodies. Due to their hallucinogenic effects, many Psilocybe species, including P. mexicana, are ingested recreationally. Although the recreational use of Psilocybin species often calls to mind the “psychedelic underground- of hippies, freaks, and travelers,” so-called “magic mushrooms” have been used for at least hundreds, perhaps thousands, of years by indigenous civilizations around the world, particularly those of Mexico (Letcher 3). Anthropological research has indicated that “at the time of the Spanish invasion, psychoactive mushrooms were being consumed in a variety of religious, secular, recreational, and even diplomatic contexts within the dominant Mesoamerican Aztec civilization” (Letcher 76). Despite frequent association with both recreational and Mesoamerican ritualistic use, psilocybin-containing mushroom species also offer potential medicinal value. For example, administration of psilocybin is being assessed in pilot studies for its potential to alleviate anxiety, depression, and/ or pain associated with advanced or potentially life-threatening cancer, perhaps through inducing spiritual experiences associated with increased well-being (“Psilocybin Advanced…” and “Psychopharmacology…”).