Psilocybe caerulipes, commonly known as blue-foot, is a rare psilocybin mushroom of the Strophariaceae family, having psilocybin and psilocin as main active compounds. An older synonym is Agaricus caerulipes. It is in the section Semilanceatae.
Cap: 1 — 3.5 cm in diameter, obtusely conic to convex, margin initially turned inwards, later becoming broadly convex to flattened or somewhat umbilicate while retaining a slight umbo, at times quite irregular, surface viscid when moist from a gelatinous pellicle, but soon becoming dry and shiny, translucent-striate, and decorated with fine fibrillose veil remnants near the margin, often with greenish stains near the margin or a greenish tinge overall. Cinnamon brown to dingy brown when fresh, hygrophanous and soon fading to dingy ochraceous buff to cinnamon buff. Flesh thin, pliant, bruising blue, sometimes slowly.
Gills: Close to crowded, narrow with adnate to sinuate to uncinate attachment. They are light brown at first, becoming rusty cinnamon as the spores mature, edges whitish and slightly fimbriate.
Spores: Dark purple brown, ellipsoid, 7 — 10 × 4 — 5 µm from 4-spored basidia, thick walled, with a broad germ pore. Spores from 2-spored basidia are larger.
Stipe: 3 — 6 cm long, 1.5 — 3 mm thick, equal to enlarging downwards, tough, whitish to buff at first. Pallid to bluish when dried, becoming dingy brown towards the base with age, bruises blue, sometimes slowly. Surface powdered at the apex, and covered with whitish to grayish fibrils downwards. Flesh stuffed with a pith and solid at first but becoming hollow, lacks an annulus but sometimes remnants of the thin cortinate partial veil form a soon disappearing fibrillose annular zone in the upper region of the stem.
Odor: Raphanoid when fresh to slightly farinaceous.
Microscopic features: Basidia 2 and 4 spored. Pleurocystidia absent. Cheilocystidia 18 — 35 × 4.5 — 7.5 µm, langeniform (swollen at the base, narrowed at the top), with a thin neck, sometimes forked, 1 — 2.5 µm broad at apices.