Common Collybia (Gymnopus dryophilus) — identification, habitat & look-alikes

The common collybia is one of the most common little brown mushrooms in North American woods, growing from leaf litter and rotting wood from spring through fall. Look for a reddish-brown cap that fades to tan, crowded white gills, and a thin, smooth, hollow stem. It's also called the oak-loving collybia.

Appearance

Appearance: Cap ½–3 in (1–7.5 cm) across, convex when young, flattening with age. Dark reddish brown at first, fading to tan or pale buff. The stem is ½–4 in (1–10 cm) tall, smooth, soon hollow, often with thin white threads at the base.
Growth form: Grows alone, scattered, in loose clusters, or in arcs and .

Look-alikes

Buttery collybiaRhodocollybia butyracea

The stem is usually somewhat club-shaped, thicker toward the base. A is cream to pinkish buff rather than white, but the difference is subtle.

Why they get mixed upBoth are reddish-brown, fading caps with white gills in forest litter.

Gymnopus subsulphureus

Has a yellow cap and yellow gills, plus pinkish-yellow threads at the stem base.

Why they get mixed upOne of the species proposed to be split from this one; very similar in shape and habit.

Gymnopus earleae

Cap is often dark when young, the gills are yellow, and the threads at the stem base are dark tawny. Telling the two apart for sure takes a microscope.

Why they get mixed upOne of the species proposed to be split out of the oak-loving collybia group.

Where it lives

Typical habitats: hardwood forests
conifer forests
mixed woods
wood chip mulch
Range: Found throughout North America, and in temperate woodlands of Europe as well.
Preferred conditions: Grows from leaf litter, twigs, rotting wood, and wood chip mulch, from spring through fall (and into winter in warm areas). Despite the name, it isn't picky about oaks and turns up under other hardwoods and conifers too.

Life cycle

Reproduction: Spores form on the gills and drop as a white to pale cream spore print.

Cautions

Cautions: Some guides list it as edible but not worthwhile; others report it can cause severe stomach upset. The stem is tough. It can take up mercury, so mushrooms from roadsides or industrial sites are a particular concern.

Name and classification

About the name: Long known as Collybia dryophila. Mating studies have found at least 11 interbreeding groups under this name, and researchers have proposed splitting off at least five species, four of which occur in North America. These splits aren't widely used yet.