Gymnopilus junonius

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. Cap

   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.

2. Gills

   Narrowly attached to the stem; close; short-gills frequent; orangish yellow at first, becoming orangish to orange-brown; staining brown.

3. Stem

   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.

4. Flesh

   Orangish yellow; thick and firm; not changing when sliced.

5. Odor and Taste

   The smell is not distinctive and the taste is bitter.

6. Spore Print

   Rusty orange to rusty brown.

7. Habitat

   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.

8. Chemical Reactions

   KOH red, then promptly black on cap surface.

9. Microscopic Features

   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

1. Gymnopilus penetrans

   Can look similar but this lacks the ring on the stem.

2. Phaeolepiota aurea

   Has a yellowish spore print.

3. Omphalotus illudens

   Lacks a veil and has a whitish-cream spore print.

4. Galerina marginata

   The cap is smaller and browner.

5. Desarmillaria caespitosa

   Has a white spore print, but has no ring.

6. Gymnopilus ventricosus

   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.

Sources:

Photo 1 - Author: Lukas from London, England (Creative Commons Attribution-Share Alike 2.0 Generic)

Photo 2 - Author: Tony Wills (Creative Commons Attribution 2.5 Generic)

Photo 3 - Author: Agnes Monkelbaan (Creative Commons Attribution-Share Alike 4.0 International)

Photo 4 - Author: Lukas from London, England (Creative Commons Attribution-Share Alike 2.0 Generic)

Photo 5 - Author: Jose Angel Urquia Goitia (Creative Commons Attribution-Share Alike 4.0 International)