Bear Lentinus Identification Guide

The First Impression

You are working along a dead hardwood log in autumn — a fallen beech, birch, maple or oak, bark half gone, the wood already softening. Along the flank of the log is a row of small stalkless brackets, kidney- or fan-shaped, overlapping in shingled tiers. From a distance they might be young oyster mushrooms or one of the many small bracket fungi, but two things stand out on closer approach: the cap surface is matt and hairy rather than smooth, and it is darkest at the point of attachment, shading paler outwards.

Turn one over and the identification effectively falls into place. The underside carries proper gills, radiating from the attachment point, and their edges are unmistakably ragged — deeply and irregularly saw-toothed, as if someone had gone along each gill with pinking shears. That torn, toothed gill edge is the defining feature of this whole group and is the character to check first, last and always.

Reading the Cap

Individual caps are 2 to 10 centimetres across, semicircular, kidney-shaped or shell-shaped, and attached to the wood directly along one edge or by a narrow fused point. Young caps have a strongly inrolled margin; older ones flatten and often become wavy, lobed or split.

The surface texture is the second key character. Near the attachment the cap is densely and coarsely hairy or velvety, sometimes almost shaggy, with a distinctly tomentose feel under a fingertip. That hairiness thins towards the margin, which may be almost smooth. Colour follows the same gradient: dark brown, reddish-brown or umber at the base, fading through tan and cinnamon to buff or nearly whitish at the outer edge. The overall effect is of a small furred bracket with a pale rim.

Wet weather darkens the whole cap and mats the hairs down, so in rain the velvety texture is easier to feel than to see. Dried specimens go hard and the hairs stand out again.

Gills and Attachment

Examine the underside with a hand lens if you have one.

Gills are moderately close to fairly crowded, whitish to cream when young, ageing to pale tan, pinkish-buff or dull brown. They radiate outward from the lateral point of attachment, which may be an eccentric spot at the back of the cap or a broad line along the rear edge. Gills of different lengths are interleaved, and near the attachment they may branch.

Now the edges. Under a lens, each gill edge is coarsely and irregularly serrate — a run of uneven pointed teeth, not a fine even fringe and not the smooth clean edge of an oyster mushroom. On mature specimens the effect is visible without magnification if you tilt the cap into the light. Nothing else with this growth form on hardwood shows so clearly torn a gill edge.

Stipe, Flesh and Section

There is no stipe. Fruiting bodies attach directly to the wood, and the point of attachment is often thickened, slightly hairy and darkened but never drawn out into a stalk. If your specimen shows a distinct if rudimentary stalk-like base, note it carefully, because that pushes you towards a close relative.

Cut a cap in half from the attachment outward. The flesh is thin, white to pale buff, and tough — leathery and pliant rather than soft and snapping. It bends before it breaks, and old caps become almost hard. There is no colour change on cutting: no blueing, no reddening, no blackening. Nothing exudes from the cut surface. The smell is faint and nondescript.

That toughness is a genus-level clue in itself. If your bracket is soft, watery and easily crumbled, reconsider the identification.

Taking a Spore Print

Because the fruiting body is sessile and awkwardly shaped, set the print up with a little care. Cut a cap away from the wood with a thin slice of substrate if necessary, trim the back so the cap will sit level, and place it gill-side down on white paper or a glass slide. Cover with a bowl and leave for six to twelve hours; tough-fleshed species can be slow to drop spores, and a dried-out cap may not drop at all, so choose a fresh specimen and add a damp tissue under the cover.

The deposit is white to very faintly cream. That immediately eliminates the small brown-spored brackets that share this habitat.

Under a microscope the spores are small, roughly spherical to broadly elliptical, and minutely spiny, and they turn blue-black in iodine solutions, an amyloid reaction that is characteristic of the genus and a decisive confirmation if you have the reagent.

Substrate, Season and Ecology

This is a wood-decay fungus, a white-rot species that breaks down lignin and cellulose in dead hardwood. Its typical substrates are fallen logs, large branches, stumps and standing dead trunks of broadleaf trees — beech, birch, maple, oak, alder and others — usually at a middle stage of decay when the bark is loosening but the wood still holds its shape. It fruits far less often on conifers.

Fruiting peaks in late summer and autumn, with occasional appearances in mild spells outside that window. Fruiting bodies commonly occur in dense overlapping tiers, sometimes running for a metre or more along a single log, and because the flesh is tough the caps persist and weather rather than collapsing, so aged brown specimens are found long after the flush.

Separating It From Look-Alikes

Lentinellus vulpinus. The closest relative and the real test. It typically has a more developed, tapered, stalk-like base rather than a completely sessile attachment, its cap is paler — whitish, cream or greyish-buff — and often warty or ridged near the base as well as hairy, and it usually grows in dense fused clusters with the individual caps crowded and distorted. This species is darker brown, more evenly velvety, and strictly sessile.

Lentinellus montanus and relatives on conifer wood. Similar gill serration, but found on conifer logs, often near melting snow at altitude in spring.

Oyster mushrooms (Pleurotus species). Smooth, hairless caps, soft flesh, and gill edges that are perfectly smooth. Feel the cap and look at a gill edge and the distinction is immediate.

Mock oyster (Phyllotopsis nidulans). Densely hairy like this species but bright orange to buff-orange throughout, with smooth gill edges and a strong smell.

Panellus stipticus. Much smaller, tan to buff, with a short distinct lateral stub of a stalk and smooth-edged gills.

Crimped gill (Plicaturopsis crispa). Small, thin, with crimped wavy folds on the underside rather than true blade-like gills, and a banded orange-brown cap.

Gilled polypores such as Lenzites betulina. The underside consists of tough, rigid, non-shattering gill-like plates continuous with the corky flesh, and the cap is concentrically zoned and often greenish with algae; the whole fruiting body is far harder than any Lentinellus.

Crepidotus species. Soft, thin, pale, sessile and easily confused at a glance, but the spore print is brown, which settles it in one test.

Field Checklist

Dead hardwood log or stump; overlapping stalkless fan- to kidney-shaped caps; densely hairy or velvety surface, dark brown at the attachment fading paler outwards; whitish to tan gills with coarsely saw-toothed edges; no stipe; tough thin white flesh with no colour change; white spore print; late summer and autumn.