Spectacular Rustgill vs Green-Staining Gymnopilus
Gymnopilus junonius compared with Gymnopilus viridans — how to tell them apart in the field.
This is a dangerous confusion.
At least one of these species is toxic. Never eat a wild mushroom based on a photo comparison alone — verify with local experts.
Spectacular Rustgill
Gymnopilus junonius
Green-Staining Gymnopilus
Gymnopilus viridans
How to Tell Them Apart
A rare Pacific Northwest species that develops greenish stains on the cap and stem with handling or age. Smaller than G. junonius (caps 3–10 cm), grows on conifer wood rather than hardwood, and lacks the prominent membranous ring. Also contains psilocybin. The green staining reaction is the key distinguishing feature.
Larger (caps up to 18 cm), grows primarily on hardwood rather than conifers, has a prominent membranous ring, and lacks the green staining reaction. Also contains psilocybin in some populations. The intense bitter taste is shared by both species.
Side-by-Side Identification
| Trait | Spectacular Rustgill | Green-Staining Gymnopilus |
|---|---|---|
| Cap | 5-18 cm across. Convex, expanding to broadly convex or nearly flat. Bright golden-orange to tawny-orange, sometimes with a slightly darker center. Surface is dry, smooth to slightly fibrillose or scaly. Flesh is thick, firm, and yellow. | 3–10 cm across. Convex when young, expanding to broadly convex or nearly flat with age. Surface dry, fibrillose to slightly scaly. Color ranges from tawny-orange to golden-brown, developing greenish to olive-green stains with handling or age. Margin may be slightly inrolled when young. |
| Gills | Attached (adnate to slightly decurrent). Bright yellow when young, becoming rusty orange-brown as spores mature. Crowded. Edges may be slightly uneven. | Attached (adnate to slightly decurrent). Moderately crowded. Pale yellow to rusty orange as spores mature. May develop greenish tones near cap margin. Edges slightly uneven. |
| Stem | 5-15 cm tall, 1-3 cm thick. Solid, firm, yellow to orange-brown. Has a membranous ring (annulus) in the upper portion that is often stained rusty by deposited spores. Base often slightly swollen. Flesh is yellow and fibrous. | 4–10 cm tall, 1–2.5 cm thick. Solid, fibrous. Pale yellowish to tawny, often with a fibrillose or slightly scaly surface. Partial veil may leave a faint ring zone that catches rusty spore deposits. Base may show greenish staining. |
| Spore print | Rusty orange to bright orange-brown. | Rusty orange-brown. |
| Odor | Not distinctive, sometimes faintly mealy. The taste is intensely and persistently bitter, which is a key identification feature. | Not distinctive. Taste bitter, as with most Gymnopilus species. |
| Habitat | Saprotrophic, occasionally weakly parasitic. Grows in dense clusters at the base of hardwood stumps and logs, especially oak, beech, and maple. Also found on buried roots, causing it to appear to grow from the ground. Occasionally on conifers. Common in deciduous and mixed forests, parks, and urban tree plantings. | Saprotrophic on dead conifer wood. Found on fallen logs, stumps, and buried roots in moist coniferous forests. Prefers mature and old-growth stands of Douglas fir, western hemlock, and Sitka spruce. Fruits in small to medium clusters. |
| Season | Autumn, typically September through November in temperate regions. Peak fruiting in October after sustained autumn rains. Can appear earlier or later depending on local conditions. | Late summer through autumn, typically August through November. Most collections are from September and October during the wet season in the Pacific Northwest. |
Found one of these in the wild? Don't rely on memory — identify it from a photo with Orangutany and check it against both species before you touch it.