Macroscopic feat.:

• Cap/Pileus: 0.5-4 (5) cm broad. Conic to conic-campanulate, expanding to convex to broadly convex to nearly plane, often undulating and umbonate. Surface smooth, shortly translucent-striate along the margin. Reddish brown to vinaceous brown, hygrophanous, fading in drying to a pale orangish light brown from the center to the margins, which are often tinged bluish green. Flesh whitish, quickly bruising bluish where injured.
• Gills/Lamellae: Attachment adnexed to sinuate, close, pale-pinkish brown, becoming dark chocolate brown with spore maturity, with similarly colored or slightly paler edges.
• Stem/Stipe: 20-60 (100) mm long by 2-7 mm thick. Equal to enlarging upwards, covered with fine fibrillose veil remnants, especially when young, smooth in age. Pale pinkish white, bruising bluish where injured. Partial veil finely cortinate, leaving fragile patches of fibrils, soon disappearing. Flesh pinkish brown, tough, hollow, quickly bruising bluish when handled.

Microscopic feat.:

• Basidio/Spores: Dark violaceous brown in deposit, subellipsoid to ellipsoid-ovoid, 6-9.9 by 3.8-4 µm.
• Basidia: 4-spored.
• Pleurocistidia: Absent.
• Cheilocystidia: 16-24 by 3.5-6 µm, sublageniform with an elongated neck, 1.5-3 µm thick, sometimes forked or mucronate.

Habitat: Gregarious to cespitose in muddy and swampy soils on the walls of ravines in fir (Abies) and pine (Pinus) woodlands. Found August through September in Mexico (state of Mexico).

Comment: Potently active, judging by the strength of the bluing reaction. The name Psilocybe wassoni was preempted by Smith and Singer's publication of the name just 24 days prior to the publication of Heim and Wasson's (1958) masterpiece, and given the international rules governing nomenclature, the name first published presides. Since may of Singer's Mexican contacts were provided, in good faith, by Heim and Wasson, this event created a rift between two schools of mycologists that persisted for several decades. Heim and Hofmann (1958) found 0.02% psilocybin and 0.01% psilocin in seven-month-old specimens. Undoubtedly, fresh specimens are many orders of magnitude stronger.

source - Paul Stamets "Psilocybin Mushrooms of the World"

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