Shingled Hedgehog Identification Guide

The first impression

The Shingled Hedgehog is one of the few tooth fungi you can spot from standing height. You are usually in mature spruce forest on a mossy, acidic floor, walking between straight trunks with a thick carpet of feather moss and needle litter underfoot, and what catches the eye is a broad, dark, ragged-looking cap the size of a saucer or a dinner plate sitting low on a pale stout stalk. The surface looks as though it has been tiled: coarse, thick, blackish-brown scales stand up and curl away from the cap in rough concentric rings, largest and most upright at the centre and flattening toward the edge. Once you tip the cap and see a dense bed of grey spines instead of gills, the group is settled and the rest of the identification is a matter of working carefully through the details.

Reading the cap

The cap is large, commonly 8-20 cm across and sometimes reaching 30 cm. It begins convex with a flat top and quickly develops a central depression, deepening in age until big specimens are broadly funnel-shaped with a wavy, lobed and often split margin. The ground colour is a pale to mid greyish brown, but almost none of it is visible because the surface breaks into the shingle-like scales that name the species. Those scales are coarse - several millimetres to more than a centimetre wide - thick, dark umber to almost black-brown, and distinctly raised at their free ends, so the cap has a bristling, roof-tile texture you can feel with a fingertip. The scaling is boldest over the centre and thins to fine appressed fibrils near the rim. The surface is dry throughout and never slimy.

The spore-bearing surface

Underneath, instead of gills or pores, the cap carries a crowded bed of downward-hanging spines. They are 5-10 mm long, tapering to sharp points, brittle, and clearly running some way down the top of the stalk as a decurrent skirt. In young fruit bodies the spines are pale grey to whitish; they darken through grey-brown to a dull purplish or coffee brown as the spores mature, so the underside colour is an age indicator rather than a fixed character. Rub the spines with a thumb: they crumble and detach readily, which is normal, and they leave a brown smear as the spores come away.

Stalk, base and flesh

The stipe is short and stout relative to the cap, roughly 3-8 cm tall and 1.5-3 cm thick, often eccentric and frequently tapered toward the base where it is embedded in moss. It is smooth or slightly felted, pale greyish brown to buff, sometimes with darker patches, and it lacks any ring or veil remnants. Cut the fruit body from cap edge through the stalk. The flesh is firm and fibrous but not woody or corky - it can be sliced with a knife without effort - and it is whitish, cream or pale buff, sometimes with faint greyish or vinaceous tints in the stalk. Note carefully the negatives: there is no strongly zoned or banded interior, no black core, and the cut surface changes little, at most dulling to a slightly darker brownish or greyish tone over several minutes. The odour is mealy to faintly spicy.

Getting a spore deposit

A tooth fungus prints just like a gilled one. Cut the cap free, set it spines-down on white paper, cover it with a bowl and leave it overnight. The Shingled Hedgehog gives a brown print - a clear, definite mid-brown, quite unlike the white to cream prints of the true Hydnum hedgehogs. This is the single most decisive test in the group and it is worth doing every time. Under a microscope the spores confirm it: they are subglobose to irregular, pale brown, and covered in coarse angular warts and tubercles, entirely different from the smooth ellipsoid spores of Hydnum.

Substrate, partners and season

This species is not a wood decomposer. It grows from soil in a root partnership with conifers, and in its classic form it is a spruce associate, fruiting in mature and old-growth spruce stands, upland and boreal forest, and mossy conifer plantations on acid soils. Fruit bodies come up singly, in scattered troops or in loose rings and arcs, often half-buried in moss so that only the scaly cap top shows. The season is late summer into autumn, running until the first hard frosts, and it favours cool, humid, well-shaded ground. Presence in pure spruce woodland is a meaningful supporting character, because the closest look-alike swaps its partner.

Separating the look-alikes

Sarcodon squamosus is the most serious confusion and was long lumped with this species. It partners with pine rather than spruce, typically on drier sandy or heathy ground, its cap scales are flatter, finer and more appressed rather than coarsely upturned, and its stalk base often carries a distinct violet, lilac or blue-grey tint. Check host tree, scale coarseness and stalk base colour together.

Sarcodon scabrosus is smaller with a browner, more finely scaly cap and, decisively, a stalk base with a blue-green to blackish-green zone visible in section.

Sarcodon fuligineoviolaceus and its allies show violet tones in the flesh, particularly in the stalk.

Hydnum repandum and Hydnum rufescens, the true hedgehogs, share the toothed underside but nothing else: their caps are smooth, matte and pale apricot to buff with no scaling at all, their spines and flesh are white to cream and soft rather than fibrous, and they drop a white to pale cream spore print.

Hydnellum species can be brown, scaly-topped and toothed, but their flesh is tough and corky - hard to cut, impossible to bend - and in section it shows distinct concentric zones or bands. They also commonly fuse around twigs and grass stems and incorporate debris into the cap.

Phellodon species are smaller with tough blackish flesh, white-tipped spines and a white spore print.

Bankera species have pale, unzoned flesh and a white spore print, and their caps are less coarsely scaled.

The working sequence

Big funnel-shaped cap with coarse, raised, concentric dark scales; crowded grey to brown decurrent spines beneath; short stout pale stalk without a ring; firm unzoned pale flesh with little colour change; brown spore print with warted spores; from soil under spruce in autumn. That is Sarcodon imbricatus.