Russet Toughshank

Gymnopus dryophilus, for a long time known as Collybia dryophila, is a familiar and abundant litter agaric across the temperate Northern Hemisphere. The genus name means naked foot, a reference to the smooth, hairless stems that distinguish these fungi from the woolly-footed relatives.

It is one of the earliest agarics to appear each year and one of the last to stop, fruiting from late spring through to hard frosts wherever there is deep hardwood litter. Troops of dozens of caps in an oak wood are typical, sometimes forming rough arcs.

The species is variable in colour and has been split by some authors into several closely similar taxa, so the name is often used in a broad sense for a group of russet-capped, white-gilled, slim-stemmed litter mushrooms.

Cap

The cap is 2-6 cm across, convex then flat and sometimes with a shallowly depressed centre, smooth, bald and slightly greasy when damp. It is hygrophanous, tan to rusty russet or reddish brown when moist and drying to pale buff or cream from the centre outward, so mixed troops show a wide range of shades.

Gills

Gills are white to very pale cream, narrow and notably crowded, and are narrowly attached to the stem or almost free.

Stipe

The stem is 3-7 cm long and 2-5 mm thick, smooth, hollow, cartilaginous and tough, coloured yellowish to reddish brown and usually paler at the apex, often slightly swollen or club-shaped at the base where a little white mycelium binds the leaves.

Flesh and spore print

Flesh is thin, whitish and pliant, unchanging when cut. The spore print is white to pale cream.

The Russet Toughshank grows in leaf litter, chiefly under oak but also under beech, birch and other broadleaves, and frequently in conifer needle litter as well. It also colonises woodchip, garden mulch and hedgerow litter.

Fruiting extends from late spring to late autumn, longer than for most litter agarics, and the species occurs throughout Europe, temperate Asia and North America. It is often the most numerous mushroom in an oak wood in early summer.

This is a litter saprotroph, breaking down fallen leaves and fine debris and forming extensive mycelial mats that bind the litter layer. Its long fruiting season reflects rapid colonisation of freshly fallen and partly decayed material alike.

Fruit bodies are frequently parasitised by Syzygospora mycetophila, a jelly fungus that produces pale brown, brain-like galls on the cap and stem, deforming the mushroom. Finding these gnarled growths is itself a useful clue to the host's identity.

Gymnopus ocior is very close but has a darker red-brown cap and distinctly yellow gills. Gymnopus aquosus fruits mainly in spring, has a paler pinkish-buff cap, a swollen stem base and conspicuous white root-like rhizomorphs. Gymnopus erythropus has a strongly reddish, more slender stem.

Rhodocollybia butyracea is separated by its greasy cap surface, distinctly club-shaped stem base and pale pinkish spore print. Marasmius oreades, in grassland rather than woodland, has widely spaced gills, a tougher solid stem and a broader umbo.