Tripe Fungus Identification Guide

First impression and setting

Tripe Fungus is a hedgerow and parkland species you tend to meet on a big dead hardwood: a standing elm skeleton, a fallen trunk in a churchyard, an old stump behind a car park, a wind thrown ash by a track. The first impression is of long horizontal rows of shaggy grey brackets, tier upon tier, sometimes running for a metre or more along a trunk and cloaking the wood entirely. In wet weather the colony has a soft, rubbery, slightly sinister look; in dry weather it hardens into a dark crust that most walkers pass without a glance.

Get close and there are two contrasting surfaces to read, and the contrast is the identification. The top is hairy, dull and zoned like a bracket fungus. The underside is smooth to wrinkled, gelatinous and coloured a startling purplish grey. Almost nothing else combines those two things.

The growth form

The fungus is effused reflexed: it begins as a flat crust spreading over the wood and then turns its outer margin outward and upward into a shelf. Individual brackets project only 2 to 5 cm and are thin, but they fuse laterally into long undulating tiers so the impression is of a continuous frill rather than discrete caps. On the underside of a fallen log the reflexed part may barely develop, leaving a resupinate sheet with a rolled edge.

The upper surface is densely hairy, felted to velvety, and marked with concentric zones in grey, buff, brown, ochre and sometimes olive where algae have colonised the hairs. Margins are wavy, lobed and often paler, sometimes almost white at the actively growing edge. The overall silhouette is ragged rather than neat.

The fertile face

Turn the log or crouch beneath the brackets and inspect the underside, which is where the spores are produced. It is purplish brown to violet grey, sometimes reddish brown or almost liver coloured, and it is wrinkled, folded and irregularly veined into a network of low ridges and depressions. That folded pattern, evoking the lining of a stomach, gives the fungus both its English name and its species epithet.

There are no pores, no gills and no spines. Check with a hand lens, because from a distance the wrinkles can suggest coarse pores and lead the eye towards the bracket fungi. Under magnification the ridges are simply undulations of a continuous smooth fertile layer.

Texture, section and colour change

The consistency is the third pillar of the identification. Fresh material is gelatinous and rubbery, elastic enough to bend double and spring back, and it must be cut with a sharp blade rather than torn. Cut a bracket through in section with a razor and you should be able to make out three layers: a hairy upper zone, a thick translucent gelatinous middle, and the darker fertile layer beneath.

Bruising and cutting produce no dramatic colour change. Drying produces the biggest transformation of all: the fruit body contracts into a hard, dark, brittle crust, only to swell back to full rubbery form within hours of rain, a cycle it can repeat many times. If you find a hard black crust with a hairy top on an elm log in a dry spell, wet it and come back.

Taking and reading the spore print

Because the deposit is white, print onto dark card or onto black paper rather than white. Cut a well hydrated bracket free with a knife, taking a piece of the substrate if necessary, and suspend or prop it fertile side down over the card inside a closed box with a scrap of damp tissue to keep the humidity up. Eight to twelve hours usually gives a visible white bloom.

Under the microscope the spores are large, smooth, colourless and allantoid, that is, curved and sausage shaped. A squash of the fertile layer also shows the basidia divided by transverse cross walls into four cells, the arrangement characteristic of this group and quite different from the four celled longitudinally divided basidia of Tremella. Between them, curved spores plus transversely septate basidia are conclusive.

Substrate, decay and season

This is a white rot fungus of dead hardwood. Elm is the classic host and long dead elm remains its strongest association, but ash, beech, sycamore, maple, poplar and other broadleaves are all used, most often as standing dead trunks, stumps and large fallen limbs in hedgerows, parks, gardens and open woodland rather than in dense forest interiors.

Fruit bodies are effectively present all year, since they persist and rehydrate, but they are at their most conspicuous and best coloured in autumn and winter after prolonged rain. A colony can occupy the same trunk for several seasons, expanding along it year on year.

Separating the closest look-alikes

Jelly Ear, Auricularia auricula-judae, is the nearest relative. It forms distinct ear or cup shaped, stalked to laterally attached fruit bodies rather than long tiered rows, is tan to date brown rather than purple grey, has only a fine short down above rather than a dense felt, and shows a smoother inner face with fewer, broader veins. Its favourite host is elder, whereas Tripe Fungus prefers big timber and elm in particular.

Hairy Curtain Crust, Stereum hirsutum, shares the hairy, zoned upper surface and effused reflexed habit, and grows in the same places. Turn it over and the difference is immediate: the underside is smooth and bright yellow to ochre, never purplish, and the flesh is thin, dry and leathery. It snaps when dry rather than swelling rubbery when wet.

Turkeytail, Trametes versicolor, and Hairy Bracket, Trametes hirsuta, also present zoned, sometimes hairy caps in tiers, but both have a distinctly pored underside, white to cream, with pores visible to the naked eye or a weak lens, and both are tough and corky rather than gelatinous.

Wrinkled Crust, Phlebia radiata, produces bright orange to pinkish resupinate patches with radiating wrinkles and a waxy gelatinous texture, but it lies flat on the wood, forms only a narrow raised rim at most, and lacks the dense hairy upper surface.

Crimped Gill, Plicaturopsis crispa, forms small brackets with a white margin whose undersides carry folded, blunt, gill like veins in radiating lines, quite unlike the irregular network here, and it favours slender birch and beech branches.

Finally, Exidia species growing on the same logs are pure gelatinous blobs, usually black or olive, with no hairy upper surface and no bracket form at all.