Hazel Bolete Identification Guide

The First Impression

The Hazel Bolete is a sober, matt-brown bolete standing in the litter of a broadleaved wood, and the first thing that registers is that its cap looks battered. Where most boletes have a smooth, evenly domed cap, this one is uneven, dimpled and creased, as though it had been tapped all over with a small hammer. The second signal is the stem, which is pale and rough with tiny dark scales rather than smooth or netted. You are usually standing under hornbeam or hazel, often on chalky or limey ground, on a woodland path edge, a coppice floor or a hedge bank, and the mushrooms are scattered singly or in twos and threes.

Working Through the Cap

Caps measure 4 to 10 cm across, occasionally to 12 cm. They are hemispherical at first and become convex to almost flat. The colour is a muted range of ochre-brown, olive-brown, hazel, grey-brown and dark umber, sometimes almost blackish-brown on shaded specimens and paler tan in the open.

The texture is the point. The surface is dry, matt and finely felted or suede-like when young, and it is markedly uneven: pitted, dented, wrinkled and puckered, with shallow depressions and low ridges. In dry weather it cracks into a fine network of shallow fissures, and the pale flesh showing through the cracks makes the cap look like a dried-out riverbed. In wet weather it can become slightly tacky. The cuticle usually overhangs the pore layer by a millimetre or two at the rim as a narrow sterile margin.

The Pore Surface

Boletes carry a spongy layer of vertical tubes rather than gills, and the whole layer can be peeled away from the cap flesh with a thumb. Look at the pore mouths with a lens: they are small and round, whitish to pale grey-buff when young and turning dull ochre-buff, olive-grey or dingy brown with age. The tubes below are 1 to 2 cm long, pale, and adnexed to depressed around the stem apex, often with a shallow gutter.

Now press the pore surface firmly with a fingertip and wait. It stains first ochre or dull brownish, then progressively darker, ending grey to almost black at the bruise. That slow, deep, grey-black bruising is a core character of the species.

The Stipe

The stem is 5 to 12 cm tall and 1 to 2.5 cm thick, tall in relation to the cap, tapering upward from a slightly thickened base, solid and fibrous. Its ground colour is whitish or pale grey, and over that ground it is covered from top to bottom with fine, dense, granular scales, called scabers, which are pale at first and quickly darken to grey, dark brown or blackish. Rows of scabers often align vertically, giving a slightly striped effect. There is no net, no ring and no volva. Handling the stem discolours it, and the base commonly shows dirty grey-brown to blackish smudging.

Flesh and Colour Change

This is the step that clinches the identification, so do it deliberately. Slice the whole fruitbody in half lengthways, lay the halves cut face up, and watch for five minutes.

The flesh is white and firm at first. Within a minute or two it flushes pink, rose or vinaceous, most strongly in the upper stem and cap, and that pink then deepens through purplish-grey to a dark slate-grey or near-black over the next several minutes. The base of the stem often goes grey-black most quickly and most strongly. The end state is a distinctly blackened cut surface, and there is no blue at any stage. Old specimens can be waterlogged and change more sluggishly, so use a firm, fresh fruitbody if one is available. The smell is mild and pleasantly fungal.

Taking a Spore Print

Cut a slab of the cap free with the tube layer intact and lay it pore-side down on white paper, covered, for several hours. The deposit is olive-brown, snuff-brown or clay-brown, never white, pink or rust-red. Under a microscope the spores are long, smooth and spindle-shaped, typical of the scaber-stalk group.

Habitat, Partners and Season

The host tree carries almost as much weight as the morphology. This species is ectomycorrhizal and is essentially restricted to hornbeam and hazel, with hop-hornbeam in southern Europe; the older name carpini reflects that partnership with Carpinus. Look in hornbeam woods and coppice, hazel understorey, old hedgerows, scrubby wood edges and parkland with these trees, particularly on calcareous or neutral clay-loam soils. It fruits from soil and litter, never on wood, and the season runs from June through to October, with the strongest showing in late summer and early autumn after rain.

Separating It from Look-alikes

All the scaber-stalks share the rough dark-scaled stem, so the separations rest on cap texture, flesh reaction and host tree.

Leccinum scabrum, the Birch Bolete, is the commonest confusion. Its cap is smooth and evenly convex rather than pitted and hammered, the colour is a plainer grey-brown to tan, and the cut flesh barely changes, showing at most a faint pinkish or greyish tint without a strong blackening. Its host is birch.

Leccinum variicolor also grows with birch, has a mottled grey-brown streaky cap, and its cut flesh turns pink in the cap but blue-green in the stem base, a reaction absent here.

Leccinum duriusculum has a firmer, paler cap, grows with poplar and aspen, and its flesh reddens then turns grey-blue in the base.

Leccinum versipelle and its allies have vivid orange to brick-orange caps with a wide overhanging margin and dark blackish scabers, and the flesh goes wine-grey then black; the cap colour alone separates them.

Leccinellum crocipodium grows with oak, has a yellow-brown cracking cap, distinctly yellow pores and yellow flesh that blackens, so the yellow tones settle it.

Among other boletes, species of Boletus, Xerocomellus and Suillus lack scabers altogether; their stems are smooth, netted, dotted or ringed instead. Any bolete whose stem is granular-scaly from top to bottom belongs to the scaber-stalk group, and within that group a pitted cap plus pink-then-black flesh under hornbeam or hazel gives the Hazel Bolete.

Field Checklist

Dented, wrinkled, matt brown cap, often cracking; small pale pores ageing dingy and bruising ochre then grey-black; tall whitish stem roughened with dark scabers; flesh white turning pink then slate-grey to black on cutting; olive-brown spore print; growing from soil under hornbeam or hazel from summer to autumn.