Bruising Webcap Identification Guide

Standing In Front Of It

Almost every encounter with the Bruising Webcap happens the same way. You are in mature broadleaf or mixed woodland in autumn, walking over soil that feels loamy and base-rich rather than thin and sandy, and something bulky is shouldering the leaf litter aside. The first impression is of weight. This is not a slender litter mushroom; it is a heavy, thick-fleshed thing with a slightly tacky olive-brown cap, a stem that looks a size too broad for the cap it carries, and a dull rusty smudge encircling the upper stem like a dusty belt.

Before you touch anything, look at the surroundings. Note which trees are within a few metres, because this is a root-partner species and the tree matters. Note whether there are several fruit bodies in a loose troop or arc, which is typical. Then crouch and start reading the mushroom from the top down, saving the two decisive tests, cutting and bruising, for last.

Reading The Cap

Expect roughly 5 to 15 cm across. Young caps are strongly convex with the margin rolled well under; older ones flatten out and often go slightly irregular or wavy. The surface is viscid when damp, so litter and small fragments of leaf glue themselves to it, and it dries to a faintly greasy shine rather than a matt bloom.

Colour is the part beginners find slippery, because it is genuinely variable and genuinely marbled. The base tone is olive-brown, date-brown or a warm ochre-brown, but it is streaked with radial innate fibrils that make the surface look grained rather than evenly painted, and young caps often carry violet or purplish flushes, strongest toward the margin. Wipe a thumb firmly across the cap surface. On a fresh specimen the rubbed track darkens to purple within a minute. That reaction, on the cap alone, already narrows things a long way.

The Gills And The Cobweb Veil

Turn the cap over gently. The gills are attached and notched where they meet the stem, moderately crowded, and in young material they are a clear blue-violet to lilac. As the spores mature they run through clay and cinnamon shades and end up a definite rust-brown, so a mature specimen can look completely unlike a young one. Where possible, examine several fruit bodies of different ages together, because the sequence of gill colour is more informative than any single snapshot.

On buttons and young caps you will find the cortina, the cobwebby partial veil that gives the whole genus its name. It runs as fine, silky, faintly violaceous threads from the cap margin to the stem. It never forms a proper membranous ring. Instead it collapses onto the stem as a fibrillose zone, and falling spores dust that zone rusty brown. If you find a stout mushroom with a rusty fibrillose belt rather than a skirt, you are in webcap country.

Press a gill edge with a fingertip and wait. The bruised strip turns purple, matching the cap reaction.

Stem And Base

The stem is 6 to 12 cm long and 1.5 to 3 cm thick, firm and solid, silky-fibrillose, pale violaceous or lilac at the apex and fading to whitish-ochre lower down. The base is the character worth digging for, so excavate the whole thing with a knife rather than snapping it off. The stem swells abruptly into a bulb, and that bulb is marginate: it has a distinct rim or flange around it, as though the base had been pressed into a shallow saucer. A rounded club-shaped swelling is a different thing entirely, and telling marginate from clavate is one of the most useful skills in this group.

Flesh And Colour Change

Split a whole fruit body from cap to base with one clean vertical cut. The flesh is thick, firm and whitish, with violaceous tints that are strongest in the stem apex and in a zone just above the bulb. Now watch. Within one to three minutes the entire cut face flushes lilac and then a saturated purple, most intensely through the stem and the gill trama. It is not a subtle stain that you have to persuade yourself you can see; it is the defining feature of the species and it is why every handled specimen ends up smeared with purple fingerprints.

Taking A Spore Print

Choose a cap that has opened fully and whose gills have begun to turn brown. Cut the stem off flush, set the cap gills-down on white paper or foil, cover it with a bowl or cup to hold the humidity in, and leave it somewhere at room temperature for four hours or overnight. The print comes out rust-brown to cinnamon-brown, and it shows up best against white.

That rusty print puts you in a small set of genera. Combine it with the cobwebby veil, the violet young gills, the marginate bulb and the purple bruising, and the combination is highly diagnostic. Under a microscope the spores are almond-shaped and coarsely warted, which is the standard webcap signature.

Substrate And Season

This is an ectomycorrhizal species, so it grows from soil in partnership with living trees and never from wood. Look for it under beech and oak, and also with spruce and fir in mixed stands, on neutral to calcareous or otherwise nutrient-rich soils. The season runs from late summer through to the closing weeks of autumn, peaking after a wet spell. Fruit bodies often appear in loose groups, sometimes in rough arcs, and they frequently push up a dome of litter before they break through, so a suspicious hummock in the leaf layer is worth investigating.

Separating The Look-Alikes On Structure

Cortinarius caerulescens shares the marginate bulb and the violet tones, but its cap is a clear blue-lilac all over when young rather than olive-brown and marbled, and its cut flesh stays bluish and then fades instead of deepening to purple.

Cortinarius glaucopus also has bluish young gills and a rimmed bulb, but the cap is ochre to tawny with strongly radiating fibrils, and the flesh is whitish and essentially unchanging when cut.

The Cortinarius largus and variecolor group are paler, more lilac-brown, and crucially the base swells into a rounded club without a rim. Their flesh pales rather than purpling.

Cortinarius traganus and camphoratus are lilac outside but have dry, silky, non-viscid caps, ochre-brown gills almost from the start, more slender stems without a marginate bulb, and a conifer preference.

Lepista nuda, the Wood Blewit, is often confused with any purple woodland mushroom. Structurally it is quite different: there is no cortina at all, the base is club-shaped without a rim, the gills stay lilac rather than going rusty, and the spore print is pale pinkish-buff instead of rust-brown. The print alone settles it.

Quick Field Checklist

Stout and heavy; tacky marbled olive-brown cap; violet young gills going rust-brown; cobwebby veil leaving a rusty fibrillose belt; marginate rimmed bulb; every cut and rub turning deep purple; rusty spore print; mycorrhizal with broadleaf or conifer on rich soil in autumn.