Purplepore Bracket Identification Guide

The scene you find it in

Purplepore Bracket is a fungus of dead conifer wood, and it is one of the most abundant fungi in northern forests. Picture a spruce or fir log at the edge of a clearing, or a stack of thinnings left after felling, or a wind-snapped standing trunk with the bark loosening. Along the flanks of that wood run dense ranks of small, thin, pale brackets, fused shoulder to shoulder into wavy tiers that can march unbroken for a metre or more. From above they look unremarkable — greyish-white, sometimes tinged green with algae — and most walkers pass them without a glance. Turn one over and the identification begins in earnest, because the underside of a fresh specimen is violet.

Reading the cap

Each bracket is 1–3 cm wide, occasionally 4, and remarkably thin — often less than 2 mm through, sometimes barely 1 mm. The outline is semicircular to fan-shaped where a bracket grows alone, but they rarely grow alone; fusion into long undulating rows is the norm. The upper surface is densely hairy or velvety, whitish to pale grey, faintly marked with concentric zones that are more textural than coloured. Older specimens are colonised by green algae and can look moss-green from a distance. The margin is thin and sharp, and in an actively growing bracket it is often tinged with the same violet as the underside — a useful clue when the pore surface itself has faded.

Reading the spore-bearing surface

This is the decisive step. Fresh, young brackets have a bright lilac to violet or purplish-mauve pore surface, an unusual colour among small conifer brackets. With age and weathering it fades relentlessly, through pinkish-buff and tan to a dull greyish-brown, so by late winter the colour may be gone entirely except in a narrow band along the very margin. Always check the margin's underside last-of-all before deciding the colour is absent.

The structure of the surface changes as much as the colour. Young brackets have angular pores at roughly 3–5 per millimetre with intact walls. As the fruitbody expands, the pore walls split and erode, so the surface becomes irregular, lacerated and finally toothed, the mature bracket carrying a mat of flattened, blunt spines rather than tidy tubes. Both extremes belong to the same species and both are normal.

Attachment, flesh and section

Most brackets are sessile, attached broadly along one edge or narrowed to a lateral point of contact. On the shaded underside of logs, the fungus often grows flat against the wood as a spreading crust with only the outer edge lifted into a small shelf — an effused-reflexed form that looks quite different but keys to the same fungus.

Cut a bracket in cross-section with a blade. The flesh is a single very thin white layer, well under a millimetre, tough and leathery. When wet it is flexible and can be bent almost double without breaking; when dry it becomes stiff and hard and revives on rewetting. There is no dark line between flesh and cap surface, no zoning in the flesh, no latex, and no colour change when the flesh is bruised or cut.

Taking a spore print

The brackets are thin and their spore output is modest, so a print takes patience. Cut a fresh bracket free with a good sliver of the wood behind it, prop it pore-side-down a few millimetres above a black glass slide or dark card, and cover the whole arrangement with a bowl to hold moisture. Leave it overnight somewhere cool. The deposit is white and best read against a dark background. Under the microscope the spores are smooth, thin-walled, colourless, cylindrical and slightly curved — sausage-shaped, or allantoid — measuring roughly 6–8 µm long by 2–2.5 µm wide, and they do not react in iodine.

Substrate and season

Trichaptum abietinum is strongly restricted to conifers, above all spruce and fir, with pine, larch and Douglas-fir also used. It is a pioneer white-rot fungus of the sapwood, arriving very soon after a tree dies or a log is cut, and it is one of the first fungi to fruit on beetle-killed standing trunks. Fruitbodies are annual but tough and persistent, so brackets in every state of decay are present all year; the fresh violet flushes appear mainly in autumn and after wet spells. Finding purplish pores on a hardwood log should immediately make you reconsider the species.

Working through the lookalikes

Trichaptum fuscoviolaceum is the nearest relative and the trickiest split. It favours pine, and its spore-bearing surface is toothed or spine-like from an early stage rather than starting as regular pores and eroding later. If a young, freshly expanding bracket already has a shaggy hydnoid underside, lean towards fuscoviolaceum; if young brackets have clean angular pores that only break down with age, lean towards abietinum.

Trichaptum biforme carries the same violet margin but grows on hardwoods, and its brackets are larger, broader and thinner, with the violet fading to buff across a more extensively toothed surface. Substrate is the fastest separator.

Chondrostereum purpureum can be strikingly purple, but its fertile surface is smooth to wrinkled and waxy, never poroid or toothed, and it grows mainly on hardwoods.

Bjerkandera adusta has a grey to blackish pore surface with no violet at all, and its section shows a dark line between the white flesh and the darkening tube layer.

Stereum sanguinolentum shares conifer logs and a similar thin, hairy, greyish cap, but its underside is completely smooth, and a fresh specimen darkens red where scratched.

Gloeophyllum sepiarium is browner and thicker with a maze-like, gill-like underside of radiating plates rather than pores or teeth.

Trametes species are thicker and larger with white to cream pore surfaces and are mostly on hardwoods.

Putting it together

Conifer wood, long fused rows of thin brackets, hairy grey-white cap, and a fertile surface that is violet when fresh and progressively fades and breaks into teeth with age. White spore print with tiny curved sausage-shaped spores. Flexible leathery flesh under a millimetre thick. That combination gives Trichaptum abietinum with confidence, leaving only the pine-loving T. fuscoviolaceum as a genuine field question.