Gymnopilus subspectabilis

Gymnopilus subspectabilis, commonly known as the big laughing mushroom, laughing gym, or giant gymnopilus, is a species of agaric fungus in the family Hymenogastraceae which contains the hallucinogenic drug psilocybin.

It is known to grow singly or in large clumps on stumps and logs. While very similar visually to Gymnopilus junonius, this large gym has a scaly cap or occasionally a fibrous or almost smooth cap and prefers hardwoods. These large mushrooms can often be found on stumps and roots growing in large clumps or singly.

Cap: 2 $3⁄16$"–6 $13⁄16$" convex to flat with an inrolled margin when young. Dry scaly or finely fibrillose especially toward the edge, becoming more scaly with age. Pale yellow with grayish or brownish orange bruises and discoloration

Gills: broadly attached, white to pale yellow with brownish orange to light brown stains where bruised.

Stem: 3 $3⁄8$″–3 $7⁄8$″ tall and $1⁄2$″–$3⁄4$" thick. Pale yellow above the annulus and below is the same color but with gray orange discoloration. Parallel sides but tapered sharply at the base, occasionally swelling in the middle, moist, nearly scaly or finely fibrillose. Annulus is thin and membranous, almost fibrous evidence of it persisting to maturity often. Flesh is pale yellow developing brownish orange colors near the base

Spores: Rusty brown, ellipsoid, roughened or wrinkled, with distinctly  conical points, darkening in KOH 7.1–10×4.4–6.2 μm

Habitat: saprotrophic on hardwoods mainly stumps and roots

Microscopic features: pleurocystidia 21–37.3 μm long 3.8–7.2 width, scattered flask or bowling pin shaped and cheilocystidia 23.2–37.2 μm long 4.1–8.6 μm width, swelling in the center sometimes or shaped like a flask. Caulocystidia abundant above the annulus produced in dense clusters directly on the stem, bowling pin shaped occasionally cylindrical but with a distinctive head 20.1–47.5 μm long 3.8–9.3 μm width. Basidia are 4 spored club shaped to cylindrical usually constricted near the center 26.3–37.9×6.6–9.3 μm

KOH: spores darken in KOH

Taste: Bitter

Odor: strong mushroom odor

Look alikes:


 * Galerina marginata (deadly) light brown spores
 * Omphalotus illudens (toxic) yellow spores
 * Tricholomopsis sp. (Inedible) cream colored spores
 * Cortinarius sp. (Potentially toxic) rusty spores