Bleeding Tooth Fungus Identification Guide

First Impression and Setting

The find that everyone remembers is a young one. You are walking a mossy conifer forest floor, in spruce or pine, often on acid, poor, well-drained ground with a thick moss and needle mat, and there in the green is a small white lump that appears to be beaded with bright scarlet droplets. It looks less like a fungus than like something spilled. That combination, a white velvety surface studded with vivid red beads, is unmistakable while it lasts.

It does not last long. The droplets are guttation fluid pushed out by an actively growing fruiting body, so they only appear on fresh, expanding specimens in humid weather. Within days the beads dry to dull red-brown spots, then the whole fungus darkens to brown, and what you find for the rest of the season is a hard, dark, irregular lump that a passer-by would take for a piece of bark. Learning to recognise the mature stage is where the real fieldwork is.

Fruiting bodies commonly grow in troops and often fuse laterally, so several caps merge into a single lumpy mass that engulfs twigs, needles and moss stems as it expands. Finding growth that has grown around and through the litter rather than sitting on top of it is a good early clue.

Reading the Cap

A single cap is two to seven centimetres across, occasionally larger when fused. Young caps are irregularly rounded to flat with a knobbly, uneven, almost bumpy surface, and the texture is dense and velvety, like felted wool. Colour begins chalk-white to pinkish-white.

With maturity the centre browns first, so a middle-aged specimen shows a dark brown, blackish or rust-brown centre grading out to a pale, still-white growing margin. Old caps are uniformly dark brown to blackish, sometimes with a slight purplish tone, and the surface loses its velvet and becomes rough, pitted, sometimes cracked and often concentrically ridged. The margin, while it is still active, is thick, blunt and often lobed rather than thin.

Check for the droplets specifically. They emerge from pores in the upper surface, are bright red to blood-red, and sit like beads on the velvet. On slightly older specimens look instead for the dried residue: dull rusty-red pits and stains where beads used to be.

The Spore-Bearing Surface

Turn the fungus over, which usually means digging the whole thing out because it grips the litter. The underside carries spines, not gills and not pores. They are crowded, one to five millimetres long, tapering to fine points, and they run down onto the stalk to some degree.

Colour progression matters. Young spines are white to pinkish-white, matching the cap margin, then they age through pinkish-brown to purplish-brown and finally to dark brown, often keeping paler tips longest. Rub a finger across them and they feel stiff and slightly prickly rather than soft.

The presence of a toothed hymenium immediately narrows your options to a small set of genera, and the rest of the work is separating within that set.

Stipe, Base and Flesh

The stipe is short, one to five centimetres, stout, often off-centre or bent, and it tapers downward. Frequently it is largely buried in moss and litter, and it binds needles, moss and soil particles into a dense plug at the base, so extraction pulls up a clot of substrate. Colour follows the cap, whitish above at first, browning to dark reddish-brown or blackish.

Cut the whole fruiting body vertically with a strong knife, because the flesh is corky to woody and does not slice like a soft mushroom. The cut face shows two layers: a firmer, paler upper context and a darker, fibrous lower zone continuous with the spines, a duplex arrangement. Look for concentric zoning in the stipe flesh, appearing as faint dark and pale bands. The flesh is pinkish-brown to rusty brown and does not change colour on exposure. Its toughness alone separates this fungus from the fleshy toothed mushrooms.

Taking a Spore Print

Spore printing a Hydnellum requires patience because mature specimens are slow droppers and the tissue is tough. Cut a piece with intact spines from a specimen whose teeth have begun to brown, set it spine-side-down on white paper, cover with a bowl, and leave it for at least twelve hours and preferably a full day in a cool, humid spot.

The deposit is brown, in the range of warm brown to rusty brown. Under a lens the spores are subglobose to broadly elliptical and conspicuously warted or tuberculate, which is characteristic of the genus and its close relatives, and it is worth looking at with even a modest hand lens on a dark background.

Substrate, Season and Ecology

This is an ectomycorrhizal fungus of conifers, associating with pines and spruces above all. It fruits from the ground, never from wood, in mossy coniferous and mixed woodland, on nutrient-poor sandy or acid soils, and it is often found in the same stands as other tough terrestrial toothed fungi.

The season runs from late summer through autumn, and fruiting bodies persist long after they stop growing, so blackened old specimens can be found well into winter. Because the association is with living tree roots, colonies are perennial in place and expand slowly as arcs or patches, which is why one good site keeps producing.

Separating It From Look-alikes on Morphology

Hydnellum ferrugineum and H. pineticola. The closest problem, since both are pale-when-young conifer Hydnellums that can exude droplets. Their exudate is typically paler, more pinkish or watery-reddish rather than the vivid blood-red beads of H. peckii, their caps tend to be flatter and more felted-fibrous with less of the knobbly lumpiness, and their flesh zoning and colour tones run more toward rust and ochre. Where droplets are absent, separating these three in the field is genuinely difficult and is usually done on flesh colour, texture of the cap surface and microscopy.

Hydnellum caeruleum. Also produces a pale young cap, but the flesh in section shows distinct blue-grey banding in the upper context and the spines have a bluish cast when young, neither of which occurs here.

Phellodon species. Similar tough terrestrial toothed fungi, but their spore print is white rather than brown, their flesh is often blue-black to grey in the stipe, and dried specimens are noticeably lighter and more corky. A brown print rules out Phellodon.

Sarcodon species. Much larger and genuinely fleshy rather than corky, with caps that are typically coarsely scaly and brown, and a stipe you can cut easily with a pocket knife. Brown spore prints and warted spores are shared, so use texture and cap scaliness.

Hericium and other toothed wood fungi. Grow on wood, are white and soft, and have spines hanging from branched or cushion-like masses rather than from a stalked cap on soil.

Quick Field Checklist

Stalked, tough, corky fungus on soil in mossy conifer woods; young cap white and knobbly-velvety with bright red guttation beads; spines beneath, whitish ageing brown; duplex zoned flesh; brown spore print with warted spores; late summer through autumn, persisting for months.