Tripe Fungus
Auricularia mesenterica
Also called tripe ear, tripe jelly, elm ear
Tiered brackets with a hairy, concentrically zoned grey-brown upper surface and a deeply wrinkled purplish, gelatinous lower surface that gives the species its name.
Overview
The Tripe Fungus is the most bracket-like member of Auricularia. Instead of the single ear-shaped cup formed by its relatives, it produces rows and tiers of overlapping shelves that often fuse laterally into long ridges running for tens of centimetres along a fallen trunk, with a resupinate crust spreading between them.
The name comes from the lower surface, which is gelatinous, strongly wrinkled, veined and folded in a way that recalls tripe, and coloured a distinctive greyish- to reddish-purple. The upper surface, in contrast, is dry, hairy and marked with concentric bands of grey, brown and ochre.
It is a common white-rot fungus of dead hardwood in Europe and adjoining regions, particularly abundant on elm, and is one of the fungi most often found fruiting through the winter months.
How to identify it
Fruiting body
Brackets are 2–10 cm wide and project 1–5 cm from the wood, thin, flexible and often fused into tiered rows; frequently the fungus is partly resupinate, spreading as a crust with a shelving upper edge. It is attached broadly along one side, with no stipe.
Upper surface
Dry, densely hairy or felted, and conspicuously zoned in concentric bands of grey, greyish-brown, ochre and buff. Green algal growth is common on older specimens, adding a greenish cast. The margin is often paler and wavy.
Lower surface, flesh and spore print
The fertile underside is gelatinous, strongly wrinkled and veined into an irregular network of folds, and coloured purplish-grey, reddish-purple or violaceous brown, becoming darker and duller with age. There are no gills, pores or teeth. The flesh is thin, gelatinous-rubbery when moist and hard and brittle when dry, with a distinct fibrous-hairy upper layer. The spore print is white.
Where and when it grows
This species fruits on dead hardwood: stumps, fallen trunks, cut logs, dead standing trees and large branches. Elm is a classic host and it became especially conspicuous where elms died in numbers, but it also occurs on ash, beech, sycamore, poplar, willow and other broadleaves.
It is widespread across Europe and into Asia and North Africa, occurring in woodland, hedgerows, parks and urban plantings. Fruiting bodies can be found at any season and are particularly noticeable from autumn through spring, when they persist for months and revive after each spell of rain.
Ecological role
Auricularia mesenterica is saprobic and causes a white rot, decomposing lignin and cellulose so that colonised wood becomes soft, pale and stringy. It frequently colonises large-diameter dead wood and can persist on the same stump for years, refruiting from the same mycelium.
Spores are produced across the wrinkled lower surface, whose folds increase the fertile area considerably compared with a flat underside. Like other jelly fungi it tolerates repeated drying, hardening in dry weather and swelling again when wet, so a single bracket can shed spores across many separate humid periods.
Similar species
Auricularia auricula-judae is ear- or cup-shaped rather than shelf-like, thinner and more translucent, with a smoother, less densely hairy upper surface and a fertile face that is veined but not tripe-like. Auricularia cornea forms broad rubbery ears with a velvety grey top and a smooth purplish underside.
Stereum hirsutum looks similar from above, with hairy, zoned, tiered brackets, but its underside is smooth and bright yellow to ochre and its flesh is thin, tough and leathery rather than gelatinous. Trametes species have a distinctly pored underside. The decisive characters for Tripe Fungus are the purplish, deeply wrinkled, gelatinous fertile surface combined with a hairy zoned top.