Milking Bonnet Identification Guide

The Setting and the First Impression

Autumn woodland floor, deep litter, moss between the leaves, and a great many small grey mushrooms on thin stems. That is where you meet the Milking Bonnet, and it is often the most abundant small agaric present. It grows scattered or in loose troops through leaf litter, needle beds, buried twigs and mossy banks, in both broadleaved and coniferous woodland, and it also appears on heaths and in hedge bottoms wherever a litter layer accumulates.

The first impression is unremarkable: a grey-brown conical bonnet the size of a fingernail, on a wiry stem two or three times the cap width in length. What makes the species workable is that a single, easy action confirms it. Snap the stem near the middle, hold it still, and watch for a bead of white liquid. Almost no other small litter bonnet does this, and the test takes three seconds.

Reading the Cap

Caps are small, 0.5 to 2.5 cm across, conical to bell-shaped when young and expanding to broadly conical or bluntly campanulate, often retaining a low central umbo. They rarely flatten completely.

Colour is a cool grey to grey-brown, distinctly darker at the disc and paling toward the margin, which can be nearly whitish-grey. When moist the cap is translucent-striate: hold it up to the light and you can see the lines of the gills showing through the thin flesh, running from the margin most of the way to the centre. Dry specimens lose that translucency and fade to a duller pale grey, which trips people up, so judge colour on fresh material.

The surface is dry to slightly moist, never viscid, and there is no separable elastic skin that peels off as a whole, a point that matters when comparing with some other bonnets. The margin is even, sometimes minutely scalloped in age.

Reading the Gills

Gills are adnate, usually with a small decurrent tooth running a short way down the stipe apex, moderately distant rather than crowded, and relatively broad for the size of the cap, with several tiers of shorter intermediate gills.

Colour is white to pale grey, sometimes with a faint pinkish cast in old specimens, and, crucially, the gill edges are concolorous with the faces. They are not lined with a contrasting dark or red edge. Damage the gill face with a pin and a small white droplet may appear, though the latex is easier to demonstrate on the stipe.

The Latex Test, Done Properly

This is the identification. Take a fresh, turgid specimen, ideally one growing in damp litter after rain, and break the stipe cleanly across, low down where it is thickest. Hold the two halves still and watch the cut faces for ten to twenty seconds.

A drop of opaque white liquid should well out of the broken surface. It is white in all forms of the species, including the very dark and the pure white variants, which is exactly what makes it so useful. The latex does not change colour on standing, and it does not stain a tissue red, orange or yellow.

Two practical notes. Dry weather suppresses latex badly; a shrivelled specimen from a dry bank may produce nothing, so test several fruit bodies and prefer the fattest, freshest stems. And press gently rather than squeezing, because crushing the stem forces out cell contents and muddies the observation.

Stipe, Base and Flesh

The stipe is 4 to 10 cm tall and only 1 to 2.5 mm thick, cylindrical, equal, hollow, and rather rigid for its slenderness. Colour grades from pale grey-white at the apex to darker grey or grey-brown below. The upper part is finely pruinose or minutely powdery under a lens, becoming smooth and polished with handling.

The base is the second key character. Excavate rather than pull, and look at the bottom centimetre: it is clothed in coarse, stiff, white hairs, a shaggy strigose cuff that binds leaf fragments, moss and needles into a small ball. That white bristly base plus white latex is a combination worth memorising.

Flesh is very thin, pale, and watery, with no distinctive colour change on cutting beyond the latex itself. The odour is faint and not distinctive.

The Colour Forms

Three forms are commonly separated in the field and all behave identically in the latex test.

The typical form is grey to grey-brown as described. The dark form, often treated as var. nigra or as Mycena leucogala, has a blackish to very dark grey-brown cap and a dark, almost black stipe, and looks so different that beginners routinely file it as a separate species until they break the stem and get white latex. The pale form, var. candida, is entirely white or cream in cap and stem, and again gives white latex, which separates it neatly from the many small white litter Mycena species that give none.

Taking and Reading a Spore Print

Small caps give thin prints, so use several. Cut the stipes flush, arrange three or four caps gills-down on white paper with a slip of glass or foil under part of the group, cover with a cup or box to hold humidity, and leave overnight.

The print is white. Under the microscope the spores are ellipsoid, smooth, roughly 10 to 14 by 5 to 7 micrometres, and strongly amyloid, blackening blue-grey to black in an iodine-based mountant. That amyloid reaction is a good genus-level confirmation. Cheilocystidia on the gill edge are fusiform to flask-shaped and contribute to the sterile edge typical of the genus.

Substrate, Season and Ecology

The Milking Bonnet is a saprotroph of the litter layer. It fruits from fallen leaves, conifer needles, small twigs, cupules, moss and general woodland debris rather than from standing deadwood or logs, though it will use buried woody fragments. It occurs under beech, oak, birch, pine and spruce alike, and on acid heathland it fruits from litter and moss under heather.

The season is mainly late summer to late autumn, persisting into early winter in mild conditions, and fruiting is heaviest after prolonged rain.

Ecologically this is a significant species. Litter bonnets of this group are among the more capable small agarics at breaking down the tougher components of leaf litter, including lignin as well as cellulose, and given their abundance they contribute substantially to the turnover of the forest floor. A single hectare of beech wood can carry an enormous population of these fruit bodies in a good October, and the mycelium permeates the litter horizon between them.

Separating It from the Look-alikes

Mycena sanguinolenta also bleeds, but the latex is dark reddish, and its gill edges are lined a distinct reddish-brown. It is smaller and more slender and grows in similar litter, so the latex colour and the gill edge are the deciders.

Mycena haematopus bleeds a dark blood-red latex, is larger and more reddish-brown overall, has a finely toothed cap margin, and grows in tight clusters on rotten hardwood rather than scattered in litter.

Mycena crocata exudes bright orange to saffron latex that stains everything it touches, and grows in beech litter often attached to buried twigs.

Mycena galericulata is larger, tougher, grows in tufts on stumps and buried wood, has pinkish-tinged gills with obvious cross-veining, and produces no latex.

Mycena epipterygia has a viscid, elastic, separable cap skin and yellowish tints on the stipe, and yields no latex.

Mycena pura and its relatives are larger, lilac to pink-toned, with a strong distinctive smell and no latex.

Any small grey litter bonnet that produces no drop at all, after you have tested several fresh specimens, is simply not this species.

Quick Field Checklist

• Small grey-brown conical cap, translucent-striate when moist
• Adnate, moderately distant white-grey gills with concolorous edges
• Slender grey stipe that releases a white drop when snapped
• Coarse white bristly hairs on the stipe base, binding litter
• Scattered in leaf or needle litter, autumn; white amyloid spore print