Bare-toothed Brittlegill Identification Guide

The Setting and the First Look

You meet this fungus on the floor of a broadleaf wood in high summer or early autumn — an oak wood on well-drained ground, a beech hanger, a birch-fringed track edge. It comes up singly or in loose scattered groups from the leaf litter, never on wood, and the first impression is of a solid, dumpy, dull wine-coloured mushroom with a stout white stalk, sitting there with a slightly matt, unglamorous look about it.

Before anything else, confirm you are in the brittlegill genus at all. Grip the stipe and snap it: a brittlegill breaks cleanly and abruptly like a stick of chalk, with no fibrous stringiness, because the flesh is built from spherical cells rather than long threads. Flick a gill with a fingernail and it shatters rather than bending. Check that there is no ring on the stipe, no volva at the base, and no milky fluid seeping from a broken gill. Chalky snap, no ring, no volva, no latex: you are in the right genus and can start narrowing to species.

Reading the Cap

The cap is 5 to 10 centimetres across, occasionally larger, convex when young and expanding to flat or shallowly depressed in the centre. Colour is variable but consistently muted and warm rather than bright: wine-brown, dull vinaceous, brick, buff-ochre or a faded pinkish-tan, often paler and more yellowish at the centre and sometimes bleaching to almost cream in exposed spots. It rarely shows the vivid crimson or purple of the flashier brittlegills.

The surface is dry to slightly greasy in wet weather, smooth, and the skin peels back from the margin for roughly a third to a half of the radius — a physical test worth performing with a thumbnail, since some relatives peel barely at all and others peel almost to the centre.

Now the character that gives the species its English name. Look closely at the extreme edge of the cap, especially on older specimens. The cap skin stops just short of the rim, retracting slightly so that a very narrow band of white flesh, and the pale tips of the gills, are exposed beyond it as a thin pale line running around the margin. Held at the right angle, the effect is of teeth showing beneath a lip. It is subtle in young caps and obvious in mature ones, and it is the single most useful macroscopic clue for this species.

Gills, Stipe and Flesh

Turn the cap over. The gills are white at first, ageing to a pale cream, moderately crowded, brittle, narrowly attached to the stipe or almost free, and quite often forked near the stipe apex with a few short intermediate gills interleaved. Their edges are even. Rub a finger across them and they crumble; they do not have the greasy flexibility of some relatives, which is a real point of separation discussed below. With age or handling, small rusty-ochre spots may develop where the gills have been bruised or where insects have been at work.

The stipe is 3 to 7 centimetres tall and 1.5 to 3 centimetres thick, cylindrical or slightly clavate, white, dry, and finely wrinkled lengthwise. It is firm and solid when young, becoming softer and often hollowed or chambered inside with age. The base very frequently picks up rusty or ochre-brown stains, particularly where slugs or larvae have been in it, and that discolouration is normal rather than a defect.

Slice the whole mushroom in half lengthwise. Flesh is white, firm and brittle, unchanging or at most developing faint ochre tones over time. There is no blueing, no reddening and no blackening. The smell is faint and unremarkable.

Taking a Spore Print

Brittlegill identification leans heavily on the exact shade of the spore deposit, so make the print thick and read it in daylight. Cut the stipe off flush and set the cap gill-side down on white paper or, better, on a glass slide so you can scrape the deposit into a heap. Cover it and leave it for several hours or overnight.

The print is white to very pale cream — near the pale end of the brittlegill spectrum, without the deep ochre or egg-yellow of many relatives. A distinctly yellow deposit rules this species out. Judge it by pushing the powder into a thick ridge with a blade and viewing it against white paper in natural light; thin deposits mislead.

Under the microscope the spores are broadly elliptical and ornamented with low warts joined here and there by fine connectives, but for field purposes the colour of the mass is what matters.

Habitat, Partners and Season

This is a mycorrhizal species. Its mycelium sheathes the fine root tips of trees and trades mineral nutrients and water for sugars, which means it will only ever be found in the presence of a suitable partner and cannot be cultivated on wood or compost. Its usual partners are oak and beech, with birch, hornbeam, chestnut and occasionally conifers also recorded.

Look on well-drained soils, on slopes, on the edges of woodland rides and in old parkland under scattered mature trees, from midsummer through autumn. It is one of the earlier brittlegills to appear in the season, often coming up while the woods are still dry, and it is frequently common where it occurs.

Separating It From Look-Alikes

Charcoal burner (Russula cyanoxantha). The classic confusion, and the test is tactile. Its gills are soft, flexible and slightly greasy — you can bend and stroke them without them shattering, and they feel like lard under a fingertip. This species has properly brittle gills. The charcoal burner also carries lilac, violet, grey-green and slate tones in the cap that are absent here, and its cap skin does not retreat from the margin.

Russula heterophylla. Similar stature and pale cream print, but the cap is green to grey-green or olive, often finely cracked, and the margin shows no retracted skin.

Russula romellii and allied large brittlegills. Bigger, with a more strongly coloured cap and, critically, a deeper cream to ochre spore deposit. Print colour settles it.

Russula mustelina. A stout, tan to leather-brown species of mountain conifer forest, with a firmer, heavier build and different tree partners.

Brittlegills with white flesh that blackens or reddens (the Nigricantes group). Cut flesh in those species turns red then grey-black over minutes. Here the flesh stays white.

Milkcaps (Lactarius). Also brittle-fleshed, but a cut gill exudes a droplet of milky or watery latex within seconds. Always damage a gill and wait before ruling this out.

Field Checklist

Broadleaf woodland with oak or beech; dull wine to buff cap 5 to 10 centimetres; skin peeling a third to halfway; cap skin retracted at the rim exposing a pale toothed line; white to cream brittle gills; chalky white stipe with rusty base stains; white unchanging flesh; no latex; white to pale cream spore print; summer to autumn.