Yellowleg Bonnet

The Yellowleg Bonnet is a common and variable member of Mycena, distinguished among the genus by a glutinous coating on both cap and stem. Where most bonnets are dry and matt, this species is sticky to the touch in damp weather, and the cap skin can be lifted off in one elastic sheet.

It is a fungus of moss and litter rather than wood, appearing in scattered troops among Sphagnum and other mosses, in grass at woodland edges, on heathland and among conifer needles. It fruits late in the season and frequently persists into early winter.

Several varieties and closely related species have been described around it, differing in cap colour and stem tone, so the group is often referred to as the Mycena epipterygia complex. The core characters remain constant: a translucent striate pale cap with a removable skin, a slender yellow viscid stem, adnate whitish gills and a white spore print.

Cap

0.8–2.5 cm across, egg-shaped to conical at first, expanding to bell-shaped or broadly convex. Pale greyish-yellow, olive-yellow, straw or greyish-brown, sometimes almost white, usually darkest at the centre. Distinctly striate and translucent at the margin when moist, and covered by a slimy, elastic, separable pellicle that can be peeled off intact — the key character.

Gills

Adnate to slightly decurrent by a tooth, moderately spaced, white to pale grey or with a faint pink or yellow tint. The gill edges are also gelatinised and can be pulled away as an elastic thread, which is a useful confirmation with a hand lens and a needle.

Stipe

3–8 cm long and about 1–2 mm thick, very slender, cylindrical, hollow, smooth and conspicuously viscid or slimy when moist. Bright lemon to sulphur-yellow, sometimes paler cream above or greenish-yellow, with the base covered in fine whitish hairs. The stickiness picks up needles and grass fragments.

Flesh and spore print

Flesh is thin, pale and watery with little or no distinctive odour, and there is no latex. The spore print is white.

It grows among mosses, in grass and in litter in a wide range of habitats: conifer plantations and needle beds, damp broadleaf woodland, mossy banks, heathland, bogs with Sphagnum, dunes and even mossy lawns and roadside verges. It is often found on very rotten wood buried under moss, but is not restricted to wood.

The species is common and widespread across temperate and boreal Europe, Asia and North America. Fruiting starts in late summer, peaks through autumn, and continues into early winter, with fruitbodies persisting well in cool damp weather because the gelatinised surfaces resist drying.

The Yellowleg Bonnet is a saprotroph, decomposing plant litter, moss, needles, and small pieces of rotten buried wood. Its mycelium runs through the moss and litter layer, breaking down cellulose and lignin and returning nutrients to the soil.

The glutinous coverings on cap and stem help retain moisture, allowing fruitbodies to keep releasing spores through dry spells and late into the season when other small agarics have collapsed. Spores are wind-dispersed from within the moss layer, and the fungus fruits in the same mossy patches year after year where litter continues to accumulate.

Mycena viscosa (often treated as M. epipterygia var. viscosa) is browner-capped, more robust and grows chiefly on conifer debris, staining reddish-brown at the stem base. Mycena vulgaris is smaller, whitish to grey with a strongly glutinous cap and clearly decurrent gills, and lacks the yellow stem.

Mycena flavoalba has a pale yellowish-white cap but is entirely dry, with no slimy pellicle and no yellow stem. Small waxcaps (Hygrocybe) can be slimy and yellow, but their gills are thick, waxy and often decurrent, and their flesh is firmer. Other small bonnets such as Mycena filopes are dry, grey and have a non-peelable cap skin.