Psilocybe azurescens is a species of psychedelic mushroom whose main active compounds are psilocybin and psilocin. It is among the most potent of the tryptamine-bearing mushrooms, containing up to 1.8% psilocybin, 0.5% psilocin, and 0.4% baeocystin by dry weight, averaging to about 1.1% psilocybin and 0.15% psilocin. It belongs to the family Hymenogastraceae in the order Agaricales.
The cap (pileus) of Psilocybe azurescens is 30–100 mm in diameter, conic to convex, expanding to broadly convex and eventually flattening with age with a pronounced, persistent broad umbo; surface smooth, viscous when moist, covered by a separable gelatinous pellicle; chestnut to ochraceous brown to caramel in color, often becoming pitted with dark blue or bluish black zones, hygrophanous, fading to light straw color in drying, strongly bruising blue when damaged; margin even, sometimes irregular and eroded at maturity, slightly incurved at first, soon decurved, flattening with maturity, translucent striate and often leaving a fibrillose annular zone in the upper regions of the stipe. The lamellae are ascending, sinuate to adnate, brown, often stained into black where injured, close, with two tiers of lamellulae, mottled, edges whitish. The spore print is a dark purplish brown to purplish black in mass. The stipe is 90–200 mm in length and 3–6 mm thick, silky white, dingy brown from the base or in age, hollow at maturity, and composed of twisted, cartilaginous tissue. The base of the stipe thickens downwards, is often curved, and is characterized by coarse white aerial tufts of mycelium, often with azure tones. The mycelium surrounding the stipe base is densely rhizomorphic (i.e., root-like), silky white, tenaciously holding the wood-chips together, strongly bruising bluish upon disturbance. The fungus is odorless to slightly farinaceous, and its taste is extremely bitter.