Psilocybe mexicana is a psychedelic mushroom of the Agaricales family, having psilocybin and psilocin as main active compounds. It is a close relative to the European liberty cap. It was from this species that Dr. Albert Hofmann first isolated and named the active compounds, psilocybin and psilocin in 1958.
- Cap: (0.5)1 - 2(3) cm in diameter, conic to campanulate or subumbonate and often with a slight papilla, hygrophanous or glabrescent, even to striate at the margin, ocherous to brown or beige to straw color in age, sometimes with blueish or greenish tones, easily turning blue when injured.
- Spore print: dark purple-brown
- Spores: 8 - 12 x 5 - 8 µm. Ovoid and smooth.
- Bruising: blue or blue-green
- Gills: adnate or adnexed, gray to purple-brown with whitish edges.
- Stipe: 4 - 10(12.5) cm tall x 1 - 2(3) mm thick, equal, hollow, straw color to brownish or reddish-brown, becoming darker where injured, annulus absent.
- Veil: absent
Psilocybe mexicana is found about 4000 to 5000 feet above sea level from the South of Mexico to Guatemala, especially in limestone regions. The species grows either isolated or sparsely in moss along roadsides and trails, humid meadows or cornfields, as well as in the margin of deciduous forests. Fruiting takes place from May to October.