A large, clustered, orange to golden-brown mushroom with a membranous ring, rusty-orange spores and very bitter flesh, growing on stumps, logs and the bases of living trees. In the strict sense it is a European, Australasian and South American species; the North American 'big laughing gym' belongs to a complex of related species. It is not edible, and some members of the complex contain psilocybin.
Not edible; very bitter and toxic. European G. junonius contains bitter neurotoxic gymnopilins and lacks psilocybin, but North American look-alikes in this complex (G. luteus, G. subspectabilis) contain psilocybin, and effects of eating 'laughing gyms' range from stomach upset to hallucinations. Psilocybin's legal status varies. Separate from jack-o'-lanterns (Omphalotus: no ring, whitish spore print) and the deadly Galerina marginata (smaller, browner, amatoxins).
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Habitat
Saprobic, sometimes weakly parasitic; in dense clusters on stumps, logs, buried roots and at the base of hardwood and conifer trees, often in moist lowland woods. Summer and fall; fall to spring on the North American West Coast.
Distribution
Europe, Australasia and South America in the strict sense. Wikipedia states that true G. junonius does not occur in North America, citing Thorn et al. (2020, 'New species in the Gymnopilus junonius group'); North American look-alikes include G. luteus, G. subspectabilis and G. ventricosus. MushroomExpert still uses G. junonius for widely distributed North American material while noting that it varies and deserves new names.
Characteristics
Cap: 5-26 cm, convex becoming nearly flat, dry, finely silky or fibrillose; golden yellow to brownish orange; margin inrolled when young. Gills: narrowly attached, close; yellowish, becoming rusty orange-brown, staining brown. Stem: 9-16 cm long, 1.5-3 cm thick, equal or swollen in the middle, dull yellow to brownish orange, bruising brown; with a thin membranous ring, often dusted rusty orange by spores. Flesh: yellow, thick, firm; taste very bitter. Chemical: KOH red then black on cap. Spore print: bright rusty orange. Spores: almond-shaped, warty, dextrinoid, 8-11 x 4-6.5 um (MushroomExpert, North American material).
