Bleeding Fairy Helmet | Mycena haematopus Identification Guide

First Impressions and Where You Find It

You meet this species on wood, never on soil, and almost always in a group. The classic find is a well-rotted hardwood stump or a mossy fallen log in damp deciduous woodland, with a dense tuft of ten, twenty or more slender fungi rising from a single crack or from a patch of soft, crumbling wood. The overall impression is of small dark bells on wiry stems, in colours that sit between wine, plum, dull maroon and reddish-brown, with the caps paler and greyer toward their edges. They are delicate enough that a careless grab collapses the whole cluster, so kneel down, take the moss away from the base, and lift a few by pinching the stems low with two fingers so the base and its attachment stay intact.

Reading the Cap

Cap width runs from about 1 to 4 cm. Young ones are neatly conical or egg-shaped, then they expand to a bell shape and finally to a broadly bell-shaped or almost flat cap that keeps a low central bump. The surface is dry rather than slimy, with a very fine powdery bloom when young that a lens shows as minute frosting. Colour is deepest at the centre, a rich vinaceous brown to purplish-red, and it fades outward to pinkish-grey or fawn. Radial lines run from the margin inward, following the gills beneath, and the cap flesh is so thin that these grooves make the surface look pleated when it is wet.

The cap margin is the character worth memorising. In young and middle-aged specimens the edge is finely scalloped and carries a narrow sterile flap that hangs down slightly beyond the gills, sometimes tearing into small teeth. Hold the cap edge-on against the sky and this fringed overhang is easy to see. It gives the species a slightly ragged silhouette that a plain-edged bonnet does not have.

The Gills

Gills are moderately spaced rather than crowded, adnate to narrowly attached, and often finish with a small decurrent tooth running a short way down the stem. Fresh colour is whitish to pale greyish, sometimes with a faint pink or flesh tint as the fruit body ages. Now look hard at the gill edges with a lens. In this species the edges are essentially the same colour as the gill faces; there is no sharp dark line running along them. What you will see instead are dull reddish-brown blotches and streaks wherever the gills have been bruised, insect-chewed or handled, because the same pigment that runs in the stem stains the tissue when it is damaged. That distinction between staining where damaged and a uniformly coloured edge on every gill is the key to the closest relative.

The Stem and the Bleeding Test

The stem is 3 to 10 cm long and only 1 to 3 mm thick, hollow, cartilaginous and slightly tough for such a delicate fungus. It is coloured like the cap, purplish-brown to wine-red, often paler at the apex where a fine bloom sits, and the base is clothed in coarse whitish hairs. Those basal hairs bind the fruit body to the wood and often bring a mat of pale mycelium with them when you pull.

Now snap a stem cleanly in half, or slice it, and hold it still. Within a few seconds a drop of dark blood-red to purple-red juice wells out of the cut and hangs there. In turgid specimens after rain it beads freely and will smear your fingers; in dry weather it may only stain the broken surface. This juice is the whole point of the name and the fastest confirmation in the field. It also seeps if you tear the cap flesh, though the stem is far more reliable. Always test more than one specimen, and pick a mature but not collapsing one.

Flesh and Colour Change

The flesh is extremely thin, watery and pallid to vinaceous, with essentially no substance in the cap. Cut surfaces darken where the red juice reaches them, and old bruised material dries to dull rusty-brown marks. There is no blueing, greening or yellowing anywhere on the fruit body.

Taking a Spore Print

Cut the cap off with a millimetre of stem and lay it gills-down on a piece of glass or on black card, cover it with a cup and leave it three to six hours in a cool place. The print is white and, because the caps are small and thin, often faint, so dark card and a low-angled light help enormously. A white print, not a rusty or pink one, is what confirms you are in the bonnet group rather than looking at some small brown wood-inhabiting fungus with rusty spores. Under the microscope the spores are ellipsoid, smooth, roughly 8 to 11 micrometres long, and amyloid in Melzer's iodine, and the cap and stem surfaces carry abundant branched, warty cystidia.

Substrate, Season and Ecology

This is a decomposer of dead hardwood in the middle and late stages of decay: beech, oak, birch, maple, poplar and similar broadleaf trees. The wood is typically soft enough to press a thumbnail into, often barkless, often moss-covered, lying on damp ground in shade. Stumps, big fallen limbs and the buried remains of old logs all serve, and the fungus will fruit from a crack, a cut end, or straight out of a rotten face. Fruiting runs mainly from midsummer to late autumn, peaking after a wet spell, and clusters can reappear on the same log for several years running. Conifer wood is a poor bet.

Separating the Closest Look-alikes

• Bleeding Bonnet, Mycena sanguinolenta, also releases dark red juice, so the bleeding test alone will not settle it. Separate it on three things: it is much smaller with a cap usually under 1.5 cm; it grows singly or in scattered troops on leaf litter, needles and mossy ground rather than in tufts on rotten logs; and every gill has a distinct dark reddish-brown line along its edge, visible with a lens.
• Clustered Bonnet, Mycena inclinata, shares the tufted habit on oak and other hardwood and has a toothed cap margin, but the cap is grey-brown without wine tones, the lower stem turns a striking orange-brown to rusty yellow, and no red juice appears when it is broken.
• Common Bonnet, Mycena galericulata, is larger and greyish-buff with interveined gills that often flush pink, grows tufted on wood, and yields no coloured juice.
• Saffrondrop Bonnet, Mycena crocata, bleeds a bright orange-saffron juice instead of dark red and grows on beech litter and buried twigs.
• Milking Bonnet, Mycena galopus, releases a white juice, has a grey to grey-brown cap, and grows in litter.

Field Checklist

Tufted on rotten broadleaf wood; conical to bell-shaped wine-brown cap with a scalloped, slightly overhanging edge; pale gills that stain rusty-red where damaged but lack a dark marginal line; slender hollow stem with hairy base; dark red juice from a snapped stem; white spore print. That combination admits nothing else.