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Gymnopilus penetrans, commonly known as the Common Rustgill, is a widespread wood-rotting fungus belonging to the family Hymenogastraceae. It is characterized by its rusty orange to brownish cap, rusty orange gills, and a spore print of the same color. This species is saprobic, growing on decaying conifer wood, and is frequently encountered in coniferous and mixed forests. It is known for its bitter taste and is considered inedible, with some reports suggesting mild toxicity.
How to Identify
- Cap
- The cap is typically 2-8 cm in diameter, convex to broadly convex or nearly flat with age, sometimes with a low umbo. The color ranges from rusty orange, tawny, or yellowish-brown to reddish-brown, often darker towards the center. The surface is dry, finely fibrillose to scaly, especially when young, becoming smoother with age. The margin is often incurved when young, becoming straight or slightly wavy.
- Gills
- The gills are adnate to adnexed, sometimes with a slight decurrent tooth, crowded, and relatively narrow. They are initially yellowish to pale orange, becoming rusty orange to cinnamon-brown as the spores mature. There are numerous lamellulae (short gills).
- Stem
- The stem is 3-10 cm long and 0.5-1.5 cm thick, central, cylindrical, often slightly tapering towards the base or equal. The color is similar to the cap, yellowish to rusty brown, often paler near the apex and darker towards the base. The surface is fibrillose, sometimes with remnants of a partial veil forming an indistinct fibrillose ring zone that quickly disappears. The stem is solid when young, becoming hollow with age.
- Flesh
- The flesh is yellowish to pale orange-brown, firm in the cap, and fibrous in the stem. It has a distinctly bitter taste and a mild, sometimes slightly fungoid or radish-like odor.
- Fruiting body
- The fruiting body is a typical agaric (gilled mushroom) with a cap, gills, and a central stem. It often grows in clusters or scattered groups.
- Habitat
- Saprobic, growing on decaying conifer wood (especially pine, spruce, and fir), often on stumps, logs, or buried wood. It can also be found on deciduous wood less frequently. It grows solitarily, scattered, or in clusters.
Key Facts
- Cap surfaces: Dry, finely fibrillose to scaly, becoming smoother.
- Growth Form: Solitary, scattered, or in clusters.
- Spore Print: Rusty orange to cinnamon-brown.
- Body color: Rusty orange, tawny, yellowish-brown to reddish-brown.
- Odor: Mild, sometimes slightly fungoid or radish-like.
- Flesh bruises: Does not bruise significantly.
- Height: 3-10 cm
- Cap Diameter: 2-8 cm
- Nutrient gathering: Saprobic
Toxic
Mild ToxicityGymnopilus penetrans is generally considered inedible due to its extremely bitter taste. While not typically reported as deadly poisonous, some sources suggest it may cause mild gastrointestinal upset (nausea, vomiting, diarrhea) in some individuals. It does not contain psilocybin, unlike some other species in the genus Gymnopilus. Due to its bitterness and potential for mild toxicity, it should not be consumed.
Quick Check
- Odor: Mild, sometimes slightly fungoid or radish-like.
- Fruiting: Late summer to late autumn.
- Substrate: Decaying conifer wood (saprobic).
Where to Find
Coniferous Forests
Common in coniferous forests throughout its range, particularly where there is an abundance of decaying conifer wood.
Mixed Forests
Can also be found in mixed forests, especially if conifers are present.
Woodlands
Found in various woodland settings where suitable decaying wood substrates are available.
Finding Tips
Look for Conifer Wood
Focus your search on decaying conifer logs, stumps, and branches. It rarely grows directly on soil.
Check Under Bark
Sometimes grows from wood buried just beneath the surface or emerging from under loose bark.
Seasonal Timing
Best found from late summer through autumn, but can appear earlier or later depending on climate.
Similar Species
Spectacular Rustgill
Gymnopilus
Also known as: Gymnopilus junonius
Conifer Gymnopilus
Gymnopilus
Also known as: Gymnopilus sapineus
Big Laughing Gym
Gymnopilus
Also known as: Gymnopilus ventricosus
Scientific Classification
- Phylum
- Basidiomycota
- Class
- Agaricomycetes
- Order
- Agaricales
- Family
- Hymenogastraceae
- Genus
- Gymnopilus
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