Scaly Webcap Identification Guide

The first impression

The habitat does half the work. You are standing in damp birch woodland, often on acid ground, with a floor of moss, bilberry, heather or Sphagnum, perhaps at the wetter edge of a bog or in a boggy hollow among the trees. It is late summer or autumn. Rising from the moss are medium-sized mushrooms with dark brown caps that look distinctly bristly or shaggy in raking light, on stipes that appear to be wearing dark bands or stockings.

The overall tone is sombre: umber, cinnamon and dark brown, with none of the yellows of a rustgill or the pallor of a shield. Then you tilt a young cap into the light and see something quite unexpected against that brown palette, a soft violet or lilac flush on the young gills and at the very top of the stipe. That contrast between drab dark scales and a hidden violet is the signature of the species.

Reading the cap

Caps are 3 to 8 cm across, conical to bell-shaped when young, later convex and finally flattened with a low broad umbo. The ground colour is greyish to pale cinnamon-brown, but you rarely see much of it because the surface is densely clothed in small, dark umber to blackish-brown scales that are pointed and often erect or slightly recurved, especially over the centre and the outer half. The effect is a bristly, granular, roughened cap rather than a silky one.

The surface is dry, never viscid, which is worth confirming with a fingertip on wet material. The margin of a young cap is hung with pale fibrillose remnants of the cobwebby veil, and these frequently persist as a fringe.

The gills

Gills are moderately crowded, adnate to slightly notched at the stipe, and rather thick. The colour sequence is critical and must be assessed on a young, unopened or barely opened specimen: they begin a distinct pale violet or lilac-grey, pass through clay, ochre and cinnamon as the spores mature, and finish a plain rusty brown. In an old fruitbody all trace of violet has gone, which is exactly why finding a button in the troop is worth the extra search.

Gill edges are often slightly paler and minutely uneven under a lens. There is no green, no black and no liquefying.

The stipe, cortina and base

This is where the species is at its most photogenic. The stipe is 5 to 10 cm long and 5 to 12 mm thick, more or less equal or slightly thickened at the base, with a pale ground colour that is violaceous at the extreme apex.

Below the cortina zone, the stipe is decorated with concentric belts or girdles of dark brown to blackish woolly scales, sometimes almost forming rings, sometimes breaking into a shaggy zigzag pattern down the lower two thirds. These are remnants of the outer veil and are the character most people remember. In wet weather they mat down, so judge them on a sheltered specimen.

The cobwebby partial veil, the cortina, stretches from cap margin to stipe in young material as a fine spider-web of pale fibres. It collapses onto the stipe and catches falling spores, so mature specimens usually show a rusty band on the upper stipe where the cortina was. There is no membranous ring and no volva. The base sits in moss or wet litter with pale mycelium binding the substrate.

Flesh and colour change

Cut lengthways from cap to base. The flesh is pale greyish-buff, watery, and shows a violaceous tinge in the upper stipe in young material, fading as the fruitbody matures. There is no latex, no reddening and no strong bruising reaction; the cut surface may slowly discolour brownish. The odour is faint and unremarkable, so do not expect help from it.

Taking and reading a spore print

A print is essential in this group. Cut the stipe flush with the gills, set the cap gills-down on white paper under a cup, and leave it six to twelve hours. Webcaps are not always generous with spores, so pick a cap whose gills have already turned ochre or cinnamon.

The deposit reads rust-brown to cinnamon, distinctly warm and never purple, olive or black. That single result places the collection in the webcap genus alongside the cortina remnants. Under a microscope the spores are subglobose to broadly ellipsoid and covered in coarse warts, which is the genus norm.

Substrate and season

The species forms root partnerships with trees, and the association here is overwhelmingly with birch, generally on damp, acid, peaty or mossy ground. Wet birch carr, bog margins, Sphagnum lawns with scattered birch, and mossy slopes in northern and upland birchwood are the productive habitats. It fruits from late summer into autumn, and appears in scattered troops rather than tight clusters, sometimes running along a mossy hollow where the tree roots are.

Because the fungus is tied to living tree roots, you should always be able to see or trace a birch nearby. A collection genuinely growing on a rotten log is telling you it is something else.

Separating it from the look-alikes

Shaggy Scalycap, Pholiota squarrosa. The most frequent mistake, and the separation is straightforward once you know where to look. That species grows in large, tightly packed clusters directly on wood, typically at the base of living or dead broadleaf trunks and stumps, its cap and stipe scales are conspicuously coarse, upturned and tawny-yellow rather than dark umber, its gills go from pale yellowish to rust with never a hint of violet, and it has a fibrillose ring zone rather than the belted girdles. Clustered on wood versus scattered in moss under birch is usually enough.

Frosty Webcap, Cortinarius hemitrichus. Also a birch associate and also scaly, but the scales are whitish to pale grey and fibrillose, sitting on a greyish-brown ground and giving a frosted rather than bristly appearance, and the stipe is white-banded rather than dark-belted. Its young gills lack the clear violet flush.

Dappled Webcap, Cortinarius bolaris. Distinctive for having reddish to coppery scales scattered on a pale yellowish ground, flesh that discolours reddish where damaged, and an association with oak and beech rather than birch.

Other Telamonia webcaps. Many are brown, dry-capped and cortina-bearing. The combination to insist upon here is dense dark erect cap scales, dark belted stipe girdles, and a violet tone in young gills and stipe apex. Missing any of those, work through the group more carefully.

Fibrecaps, Inocybe species. Similar brownish scaly or fibrillose caps on soil, but they have no cobwebby cortina of this kind, their caps are typically radially fibrillose and often split at the margin, they lack violet gills, and their spore print is a dull snuff-brown rather than rust.

Scalycaps and rustgills on wood. Anything growing directly out of a stump or log with rusty gills should be checked against Gymnopilus and Pholiota rather than against a webcap, because webcaps grow from soil.

A quick field checklist

Damp mossy birch woodland, dry umber cap densely covered in dark erect scales, young gills violet before turning rust, stipe with dark woolly girdles below a cobwebby cortina zone, violaceous stipe apex, growth from soil not wood, and a rust-brown spore print.