What You Should Know
Gymnopilus junonius is a large orange mushroom that is typically found growing on tree stumps, logs, or tree bases. It has a bitter taste, a stem with a ring or ring zone, and an orange to brownish-orange spore print. Widely distributed in Europe, Australasia, and South America. It causes brown wood rot. This species does not occur in North America. However, some similar-looking species do. These include Gymnopilus ventricosus on the west coast and G. luteus and G. subspectabilis in the midwest and east.
There have been reports of this species containing psilocybin (in low amounts), but many other sources are refuting this. Hallucinogenic substances may also be present in the fruiting bodies, but these substances may also be almost completely absent). Concentrations are higher in the US and Japan than in Europe. It may also have been confused with a subspecies or look-alikes that have psychoactive effects.
Gymnopilus junonius contains bis-noryangonin and hispidin, which are structurally related to alpha-pyrones found in kava. Neurotoxins known as oligoisoprenoids have also been found in this species.
In Uruguay, it is edible and one of the most consumed mushrooms. It is used in sandwiches with a piece of beef, bacon, and other ingredients. They need to be boiled several times to remove the bitter taste.
Other names: Big Laughing Gym, Spectacular Rustgill, German (Beringter Flämmling), Netherlands (Prachtvlamhoed), Czech Republic (Šupinovka nádherná).
Gymnopilus junonius Mushroom Identification
1.97 to 10.24 inches (5 to 26 cm), convex, becoming broadly convex or nearly flat; dry; finely silky; brownish orange; the margin inrolled when young.
Narrowly attached to the stem; close; short-gills frequent; orangish yellow at first, becoming orangish to orange-brown; staining brown.
3.54 to 6.3 inches (9 to 16 cm) long; 0.59 to 1.18 inches (1.5 to 3 cm) thick; more or less equal, or swollen in the middle; silky-fibrillose, becoming balder with age; with a thin ring that sometimes folds outward at the top and collects orange spores; dull yellow to brownish orange; bruising brown.
Orangish yellow; thick and firm; not changing when sliced.
Odor and Taste
The smell is not distinctive and the taste is bitter.
Rusty orange to rusty brown.
Saprobic on the rotting wood of hardwoods and conifers; usually growing in clusters; summer and fall (fall through spring on the West Coast); widely distributed in North America.
KOH red, then promptly black on cap surface.
Spores 8–11 x 4–6.5 µm; subamygdaliform; verrucose; orangish golden in KOH; dextrinoid. pleurocystidia inconspicuous; basidiole-like. Cheilocystidia 25–35 x 2–4 µm; cylindric-flexuous with capitate to subcapitate apices; thin-walled; smooth; orangish in KOH. Pileipellis a cutis of encrusted hyphae 2.5–10 µm wide. Clamp connections are present.
Gymnopilus junonius Look-Alikes
Can look similar but this lacks the ring on the stem.
Has a yellowish spore print.
Lacks a veil and has a whitish-cream spore print.
The cap is smaller and browner.
Has a white spore print, but has no ring.
Very similar and doesn't contain psilocybin.
Gymnopilus junonius Taxonomy and Etymology
In 1821 Swedish mycologist Elias Magnus Fries described this species and named it Agaricus junonius. In 1960 British mycologist Peter Darbishire Orton (1916-2005) transferred to its present genus. The prefix Gymn- means naked, and the suffix -pilus means cap - hence naked or bald caps. The specific epithet Junonius refers to the Roman goddess Juno, daughter of Saturn and wife of Jupiter.
Gymnopilus junonius Synonyms
Agaricus junonius Fr.
Agaricus aureus Bull.
Agaricus junonius Fr. 1821
Agaricus spectabilis Weinm.
Dryophila junonius (Fries) Quélet (1886), Enchiridion fungorum in Europa media et praesertim in Gallia vigentium, p. 68
Fungus aureus (Gray) Kuntze
Gymnopilus junonius (Fries) P.D. Orton (1960), Transactions of the British mycological Society, 43(2), p. 176
Gymnopilus spectabilis A.H. Smith (1949), auct.
Gymnopilus spectabilis var. junonius (Fries) Kühner & Romagnesi (1953), Flore analytique des champignons supérieurs, p. 323
Lepiota aurea Gray
Pholiota aurantiaca Thesleff, 1920
Pholiota citrinofolia Métrod (1962) [1960-61], Bulletin de la Société des naturalistes d'Oyonnax, 14-15, p. 141
Pholiota gigantea Naveau, 1923
Pholiota grandis Rea, 1903
Pholiota junonia (Fries) P. Karsten (1879), Bidrag till kännedom af Finlands natur och folk, 32, p. 301
Pholiota spectabilis var. junonia (Fr.) J.E. Lange, 1940
Tricholoma aureum (Gray) Sacc.
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