Girdled Webcap Identification Guide

The setting you will be standing in

Girdled Webcap is a fungus of wet feet. You almost never meet it on a dry ridge; you meet it where a path dips into a willow carr, along the muddy margin of a stream, in a poplar shelterbelt on heavy clay, or in a damp dune slack where creeping willow mats the sand. The ground underfoot is often soft, the litter is sodden, and there is usually standing or seeping water within a few paces.

What catches the eye first is shine. In wet weather the caps look varnished, as if someone had poured clear jelly over them, and they collect a scatter of stuck-on debris - grass blades, willow leaves, fragments of sedge. From above, a small troop looks like nothing more than a group of medium-sized brown mushrooms. The species announces itself only when you crouch and look at the stem, which appears to be wearing a series of collapsed pale socks stacked one above another. Those belts are the whole point of the name.

Reading the cap

Work from the outside in. The cap is typically 4-10 cm across, starting distinctly convex with an inrolled margin and flattening out to a broad dome, usually keeping a low, blunt umbo. Colour runs from honey-ochre and clay through warm date-brown, generally darker over the centre and fading towards the rim. Age and rain both dull it.

The surface layer is the diagnostic bit. Run a finger across it: there is a thick, colourless, gelatinous coat that feels genuinely slippery when damp and dries to a hard, glossy, slightly tacky varnish. Debris embedded in that layer stays embedded. Lift a young cap and check the margin - you will often find pale silky fibres running from the rim down to the stem. That cobwebby veil, the cortina, is the family signature and places you in Cortinarius before you have looked at anything else.

The gills and the veil

Turn the cap over. The gills are adnate to notched at the stem, moderately crowded, and comparatively pale when young: clay-buff, sometimes with a faint greyish or weakly violet cast in the youngest buttons. As the spores ripen they shift through milk-coffee to a solid rusty cinnamon, and the gill edges stay slightly paler and a little uneven.

The change is worth tracking on a single collection. Pick two or three fruitbodies of different ages and line them up: the youngest still has an intact cortina stretched like spider silk, the middle-aged one shows a rusty smudge where that veil collapsed onto the stem, and the oldest has gills the colour of iron rust and a stem apex dusted with fallen spores. Any webcap should show that sequence, so treat it as confirmation of the genus rather than of the species.

The girdled stipe

Now the feature that settles it. The stem is 6-12 cm long and roughly 1-1.5 cm thick, usually tapering downwards, sometimes distinctly so. Above the cortina zone it is whitish, dry and silky, frequently stained rusty by spores. Below that zone it is sheathed in a glutinous universal veil that does not stay smooth. As the stem elongates the sheath tears into a series of ochre-yellow to ochre-brown, sticky, upward-pointing belts or scaly girdles, typically three to six of them, arranged like the rungs of a ladder or the rings on a boot.

Dig, do not pull. The lowest and most convincing girdles are often below litter level, and a snapped stem loses the evidence. Excavate with a knife or your fingers until you have the whole thing, then wipe mud off gently rather than scrubbing - the belts are soft and rub away easily.

Base, flesh and colour changes

The base narrows and often roots a little way into the wet humus. Split a fruitbody from cap to base with a clean cut. The flesh is white to pale ochraceous, distinctly watery in soaked specimens, and it does not do anything dramatic: no blueing, no reddening, no milk, no strong staining where you handled it. There may be a faint earthy or slightly radish-like smell, nothing striking. That absence of reaction is itself useful, because several confusable species do change.

Taking and reading a spore print

Cut a mature cap free of its stem, lay it gills-down on white paper or a glass slide, cover it with a cup to slow drying, and leave it four to twelve hours at room temperature. Expect a rusty brown to ochre-brown deposit. Scrape it into a dense patch with a blade before judging the colour - a thin dusting always looks paler and greyer than the true shade.

Under a lens or microscope the spores are almond-shaped and roughened with warts, roughly 10-14 x 6-8 micrometres. Rusty print plus cortina plus warted almond spores is a complete case for Cortinarius; the girdles then take you to the species.

Substrate and season

This is a mycorrhizal fungus, so it grows from soil in partnership with tree roots and never from wood. Its partners are willows and poplars above all, with occasional records under alder and hazel. It favours damp, often base-rich or calcareous ground and appears from late summer into late autumn, peaking after sustained rain. If there is no willow or poplar within reasonable rooting distance, be sceptical of the name, however good the girdles look.

Separating the closest look-alikes

The glutinous webcaps are a tight group, and morphology alone will get you there if you check three things: the tree, the colour inside the gluten, and whether the stem sheath is banded or continuous.

• Cortinarius mucosus grows with pine on sandy ground. Its cap is a richer rusty red-brown and its stem is white and slimy but essentially smooth, without the ladder of belts.
• Cortinarius collinitus and its relatives are conifer associates whose stem sheath carries violet or bluish tones and tends to break into finer, more irregular flecks rather than clean concentric girdles.
• Cortinarius delibutus has a clear yellow cap and, crucially, bluish gills when young and a blue-tinted stem apex; it is a birch associate and lacks the stacked belts.
• Cortinarius elatior shares the wet woodland but has a strongly wrinkled and grooved cap, violaceous tints in the stem, and a tapering, rooting stipe that is slimy rather than banded.
• Hebeloma species can look similar in colour but have no cortina, no girdles, gills that often weep droplets when young, and a duller clay-brown print.
• Pholiota species are wood-dwellers with yellowish gills and scaly rather than glutinous banded stems.

A working checklist

Slimy varnished brown cap with stuck-on litter; cobwebby veil in youth; gills clay then rusty; stem below the veil zone wrapped in several sticky pale-ochre belts; white unchanging flesh; rusty print; wet ground under willow or poplar in autumn. Tick all seven and you have Girdled Webcap.