Woolly Tooth Identification Guide

First Impression and Setting

A mossy conifer wood on poor, sandy, acid ground — old pine or spruce, thin ground vegetation, a deep floor of needles and feather moss. At first glance the thing at your feet looks like a scatter of dead leaves that have been glued together. Closer up it resolves into a rosette of small, thin, funnel-shaped caps, each concentrically banded in tan, cinnamon and dark brown with a pale outer rim, their margins fused edge to edge into an irregular sheet that flows over twigs and moss. Tilt one and the underside is unexpected: white and prickly, covered in a dense pile of short spines. That combination of zoned brown caps above and white teeth below is the whole identification in one look.

Reading the Cap

Individual caps are 1 to 5 cm across, though fused clusters can spread to 15 cm or more. They begin flat or slightly convex and quickly become centrally depressed and then shallowly funnel-shaped, often perforated right through at the centre so you can see down to the stipe. The surface is dry and, when young, distinctly felted or velvety-tomentose with a radially fibrous texture — the woolly character behind the name — becoming smoother and more matted with age. Concentric zoning is the constant feature: bands of cinnamon, russet, ochre and dark brown alternate outward, with a pale cream to whitish rim at the actively growing edge. The margin itself is thin, wavy and lobed, and where two neighbouring caps meet they simply merge, growing into one continuous, undulating plate. Debris caught during expansion is often engulfed rather than pushed aside.

Reading the Spore-Bearing Surface

Turn a cluster over. Instead of gills or pores there are teeth: crowded, slender, downward-pointing spines 1 to 2 mm long, soft-looking but firm, that run partway down the stipe rather than stopping at the cap edge, giving a decurrent tooth layer. They are white to pale grey in fresh material and darken with age and handling to grey, greyish-brown or almost purplish-grey. Rub a fingertip across them and they feel like short bristles. A hand lens shows them tapering to fine points. This toothed hymenium is the essential structural fact — it places the fungus with the hydnoid fungi and immediately excludes every bracket, polypore and gilled species.

Stipe, Base and Flesh

The stipe is 1 to 3 cm long and only 3 to 8 mm thick, central or eccentric, tapering downward, and coloured darker brown than the cap. It is densely felted and velvety, and its base is buried in a swollen, matted pad of brown mycelium that grips needles, twigs, moss stems and grains of sand into a firm ball. Where several fruit bodies grow together the stipes are often fused into a single common base.

Slice a cap and stipe vertically with a sharp blade. The flesh is remarkably thin — barely 1 to 2 mm in the cap — and it is tough, corky and leathery rather than fleshy; it will not crumble and it will not squash. In section it is two-layered, with a softer upper felt over a firmer, darker zone, and the stipe flesh is dark brown and faintly zoned. There is no colour change when the flesh is cut or bruised, and no droplets are exuded from the cap surface. As the fruit body dries, it develops a distinct sweet, hay-like fragrance that intensifies in stored specimens. A drop of potassium hydroxide solution on the cut flesh produces a blue-green to blackish reaction, a useful confirmation of the genus.

Taking and Reading the Spore Print

The spore print is the decisive genus character here and is worth the extra effort, because tough fruit bodies release spores slowly. Choose a mature cluster, trim off a single well-developed cap, and set it teeth-down on a piece of dark glass or black card with a strip of white paper beside it. Cover it with a bowl to keep the humidity up and leave it overnight, or a full twenty-four hours if the material is dry. The result is a white print. That whiteness separates Phellodon at a stroke from Hydnellum and Sarcodon, whose prints are brown. If no print appears, look in the field instead: mature specimens dust the moss, needles and neighbouring caps immediately below them with a faint white bloom. Microscopically the spores are small, subglobose and covered in fine spines, colourless under the lens at 3 to 4.5 micrometres.

Substrate and Season

Woolly Tooth is ectomycorrhizal with conifers, principally pine and spruce, so it is found only within the root zone of those trees. It favours nutrient-poor, well-drained, acidic sandy soils and old, undisturbed stands with a stable moss and needle layer — exactly the conditions that are scarce in intensively managed forest, which is why the tooth fungi as a group are so patchily distributed. Fruit bodies appear from late summer into autumn, but because they are tough and corky they persist for weeks and can still be found, dried and darkened but recognisable, well into winter. Colonies recur in the same spot year after year.

Separating the Look-alikes on Morphology Alone

Hydnellum concrescens is the closest match in appearance, with zoned, funnel-shaped, fusing caps in similar habitat. Separate it on three counts: its flesh is thicker and pinkish-brown rather than thin and dark, its teeth are pinkish to purplish-brown rather than white or grey, and its spore print is brown. Its cap surface is also more radially ridged and warty.

Phellodon connatus, sometimes listed as P. melaleucus, has a whitish-grey to blackish cap with a conspicuously pale margin, thinner and more brittle flesh, a much smoother, less felted surface, and a distinctly blackish stipe.

Phellodon niger is thicker and heavier, coloured blue-black to dark grey with a pale rim, with blue-black flesh in section and white teeth contrasting strongly against it.

Coltricia perennis grows in the same sandy conifer ground and produces almost identical zoned, velvety, funnel-shaped rusty-brown caps — but the underside carries pores, not teeth, and the spore print is brown. One glance underneath settles it.

Thelephora terrestris forms brown fan-shaped rosettes on similar soils, but its lower surface is smooth to warty or wrinkled rather than toothed, and it lacks a clear stipe and concentric cap zoning.

Sarcodon species are much larger and fleshier, with coarsely scaly caps and brown spore prints. Hydnum species have pale, thick, brittle flesh, unzoned caps and no felted texture, and belong to a different lineage altogether.

A Working Checklist

Mossy, sandy conifer woodland; small zoned funnel-shaped caps fused into rosettes; cap surface felted and radially fibrous with a pale growing rim; short white to grey decurrent spines beneath; thin, tough, corky, dark two-layered flesh with no exuded droplets; blue-green reaction to potassium hydroxide; sweet hay-like fragrance in dried material; white spore print.