Gymnopilus thiersii is a distinctive mushroom species within the Gymnopilus genus, commonly recognized as “rust gill” mushrooms. These fungi are characterized by their rusty-orange to brownish-orange spore prints, a defining feature for the genus. It is often found growing on wood.
Identifying Gymnopilus thiersii
The cap of Gymnopilus thiersii is typically conical, measuring around 5 cm wide. Its color ranges from rusty, sometimes with a bluish sheen, to shades of brown with reddish undertones. The cap surface often features scales, which are more apparent towards the center.
The gills are brownish-orange and generally not tightly compacted. They are attached to the stem, transitioning from yellowish to orange-brown as spores mature. The stem is approximately 4 cm long and 0.5 cm wide, cream-colored with an orangeish-brown tint, and feels solid. It can also appear fibrillose, composed of numerous small fibers, and may show pinkish hues that fade with age.
A rusty-orange or brownish-orange spore print is a key identifying characteristic, often observed as powdery deposits. When damaged, the flesh of Gymnopilus thiersii may bruise blue-green.
Habitat and Growth
Gymnopilus thiersii is a saprobic fungus, meaning it obtains nutrients by decomposing dead or decaying organic matter. It is most frequently found growing on dead or rotting wood, including logs, stumps, and standing dead trees. This species has been observed in diverse environments, from natural woodlands to urban settings like parklands, and can even colonize treated wood.
The mushroom typically appears during the warmer months, with fruiting bodies emerging from summer through fall. It commonly grows in clusters, although individual or scattered specimens are also observed. Its role as a decomposer contributes to the natural cycling of nutrients within its ecosystem.
Edibility and Toxicity
Gymnopilus thiersii contains the hallucinogenic compounds psilocybin and psilocin. Due to these substances, consumption of this species is not advised. Many Gymnopilus species are known for their bitter taste, which can naturally deter ingestion.
However, bitterness is not universally present across all psychoactive members of the genus. Therefore, taste should not be used as a sole indicator of edibility or toxicity. The consumption of any wild mushroom carries inherent risks, and misidentification can lead to severe poisoning.
Distinguishing From Similar Species
Identifying Gymnopilus thiersii accurately requires careful attention to its features, particularly when distinguishing it from similar-looking mushrooms. Gymnopilus thiersii bears a close resemblance to Gymnopilus luteofolius, differing mainly in subtle context colors and microscopic spore characteristics. G. luteofolius often displays a more vibrant pink-purple coloration and a distinctly scaly cap, which can help differentiate it.
A significant concern arises from its potential confusion with the deadly poisonous Galerina marginata. While both species produce a rusty-brown spore print, Galerina marginata typically exhibits yellowish-brown gills that darken to rusty brown and generally lacks the scales found on the cap of Gymnopilus thiersii. Furthermore, Galerina species are often more fragile with thin, mealy flesh, contrasting with the firmer stems and flesh of Gymnopilus. Galerina marginata also tends to have a smaller cap size, usually not exceeding 4 cm, unlike the potentially larger Gymnopilus thiersii.
Another group that can be mistaken for Gymnopilus is the genus Pholiota. Pholiota species often have a viscid, or sticky, cap surface and produce duller, brown to cinnamon-brown spores. Microscopically, Pholiota spores are smooth, a key distinction from the warty spores characteristic of Gymnopilus.