Red Banded Webcap Identification Guide

What You Are Standing In When You Find It

Picture a damp birch wood in the second half of August: bilberry and hair moss underfoot, a slight squelch to the ground, birch trunks going up pale and thin around you. That is the habitat that produces Cortinarius armillatus, and habitat is doing half the identification work before you have even bent down. The fruit body itself announces itself by bulk. Most webcaps in a wood like this are middling brown things; this one is a solid, brick-coloured mushroom with a cap commonly 5-12 cm across and a stout stalk that swells towards the ground. From a standing height it reads as a chunky brown mushroom on moss. It is only when you crouch that the feature the species is named for appears: a series of bright red-brick belts wrapped around the pale lower stalk like tape.

Reading the Cap

Work top-down and slowly. The cap starts hemispherical with a strongly inrolled margin, opens to broadly convex, and finally flattens with a low, blunt umbo. The colour is tawny to foxy brick-brown, usually deepest over the centre and fading towards the rim, and it is a warm colour rather than a grey or olive one. Run a finger across it: the surface is dry and matt, never slimy or gelatinous even in rain, and under a lens it is finely fibrillose, becoming minutely scaly or radially streaked on older caps. The margin often carries stray pale veil fibrils when young, and remains incurved far longer than you expect. If the cap you are holding is viscid, or is smooth and polished rather than fibrous, you are not in this species.

Gills and the Cobweb Veil

Tip the cap over. The gills are adnate to slightly notched at the stalk, moderately broad, and comparatively well spaced. Their colour is the genus story in miniature: pale clay to milky cinnamon in young specimens, then progressively rustier as the spores mature, ending a strong cinnamon-rust. Gill edges are marginally paler and slightly uneven.

In buttons, look for the cortina - the cobwebby partial veil that gives webcaps their name. It stretches as a mesh of fine silk from the cap margin to the stalk, and it is fleeting: within a day or two of expansion it collapses onto the stalk as a faint fibrillose ring zone. Because the spores are rusty, that zone soon gets dusted a distinct rust colour. Do not confuse this spore-stained cortina remnant, which sits high on the stalk, with the red belts, which sit lower and are a different structure altogether.

The Belts on the Stalk

This is the diagnostic feature and it deserves a careful read. The universal veil of this species is reddish, and as the stalk elongates that veil is torn into discrete transverse girdles left stranded on the surface. Typically there are two to five, occasionally up to six, spaced irregularly along the lower two-thirds. Each is brick to cinnabar red, sometimes a clean band, sometimes oblique or flaring into a small upturned collar. On elderly or rain-battered specimens the belts fade to a dull brownish red and can nearly wash out, so always check the youngest fruit body in the group before deciding a banded webcap is unbanded.

The stalk itself is 6-15 cm long and 1-2.5 cm thick, tapering upwards from a clavate to bulbous base. The bulb is a rounded swelling, not a sharply rimmed or marginate bulb sitting in a cup. Ground colour is pale buff to brownish, silky-fibrillose, and solid rather than hollow.

Flesh, Base and Colour Change

Slice a fruit body from cap to base. The flesh is whitish to pale buff, thick over the cap centre, often faintly wine-brown within the stalk base. Nothing dramatic happens: there is no blueing, no latex, no rapid reddening. At most the cut surface dulls to a pale brownish tone over many minutes. The odour is weak, slightly earthy or radish-like. In section you can also confirm that the red belts are superficial veil tissue laid on the surface rather than pigment in the flesh, which is a useful check.

Taking and Reading a Spore Print

A rusty spore print is the confirmation that you are in Cortinarius at all. Cut the stalk flush, lay the cap gill-side down on white paper, cover it with a bowl to keep humidity up, and leave it two to six hours. The deposit should come out a clear rusty brown, quite unlike the chocolate of a Psathyrella or the white of an Armillaria. Mature specimens often save you the trouble by self-printing rust onto their own stalks. Under a microscope the spores are almond to lemon-shaped, distinctly and coarsely warted, and around 9-12 by 5.5-7.5 micrometres, so the ornamentation is visible at 400x.

Substrate and Season

Cortinarius armillatus is ectomycorrhizal and, in practice, tied to birch. You will find it on soil among birch in wet woodland, on birch heath, along bog margins, and in mixed forest where birch is present as a component - the conifers around it are incidental, the birch is the partner. It fruits from late summer into mid-autumn across northern temperate and boreal regions and is often in loose troops or small arcs rather than singly. A large banded webcap under pure spruce with no birch anywhere is worth a second look.

Separating the Look-alikes

Other banded webcaps. Several relatives carry veil girdles. The conifer-associated banded species are generally smaller, with darker date-brown to chestnut caps and narrower, duller reddish belts, and they occur away from birch. Judge them on band width, cap tone and stature together, not on one character.

Webcaps red only at the base. A number of species carry red pigment at the extreme stalk base or as a diffuse blush rather than as separated transverse belts, and these tend to be broadleaf associates of beech, oak and hornbeam with smoother, more richly coloured caps. Discrete, spaced girdles versus a single basal flush is the split.

Honey mushrooms. These also grow with a ring-like structure on the stalk, but the ring is a true membranous skirt rather than a series of belts, they grow in dense clusters on wood, roots and stumps, and the spore print is white.

Scalycaps. Rusty spore prints again, but they fruit on wood, the caps are often viscid and shaggily scaly, and the stalk carries a fibrillose ring without red girdles.

Rustgills. Bright yellow-orange throughout, tufted on stumps and buried wood, with a well-formed membranous ring and no red banding.

Field Checklist

Chunky habit; dry, fibrillose, brick to tawny cap; well-spaced gills turning rusty; a cobwebby cortina in youth; two to five red-brick belts on a pale, club-based stalk; rusty spore print; and birch overhead. Get all six and the identification is secure.