Psilocybe fimetaria is a psilocybin mushroom, having psilocybin and psilocin as main active compounds.
- Cap: 1.5 — 3.5 cm in diameter, convex to plano-convex, becoming subcampanulate to broadly convex in age, with or without a sharp papilla. Surface even to translucent-striate near the margin, viscid when moist from a thick separable gelatinous pellicle. Pale reddish brown to honey to ochraceous, hygrophanous, fading in drying to yellowish olive to ochraceous buff. Flesh whitish to honey colored.
- Gills: Adnexed, sometimes sinuate or emarginate, subdistant, ventricose, whitish clay at first, eventually dark reddish brown with olivaceous hue, white fimbriate.
- Spore Print: Dark purple-brown, (9.5)12.5 — 15(16) x 6.5 — 9.5 µm, ovoid in front view, ellipsoid in side view, thick walled with a broad germ pore.
- Stem: 2 – 9 cm long by (0.5)2 – 4 mm thick. Cylindrical, flexuous, equal to slightly swollen at the base. Whitish at first, soon discoloring yellow to yellow brown from handling, reddish brown or honey brown in age, sometimes with distinctive blue tones at the base. Surface covered with whitish fibrils towards the apex, with an apical evanescent fibrillose annulus that develops from a thickly cortinate partial veil.
- Odor: Farinaceous
- Taste: Farinaceous
- Microscopic features: Basidia 4-spored. Pleurocystidia absent. Cheilocystidia (15)20 — 30(35) by (4)6 — 8(9) µm, ventricose-fusiform or lageniform with a narrow neck, often flexuous, 4 — 15 by 0.5 — 1.5 µm, occasionally branched.
Adnexed gills are a key feature of P. fimetaria
Habitat and distribution
Psilocybe fimetaria is found growing solitary to gregariously on horse or cow dung, in grassy areas, from September to November, known from Canada (British Columbia and New Brunswick), the Pacific Northwest (Washington, Oregon, and Idaho), Chile, Great Britain, and Europe. Widely distributed but not very common.