Beefsteak Fungus Identification Guide

The moment you spot it

Almost every encounter with Fistulina hepatica starts the same way. You are moving through mature oak woodland, wood pasture, an old park or a veteran hedgerow in late summer or autumn, and something low on a trunk stops you because it is simply the wrong colour for bark. From ten paces it reads as a wet, dark red tongue or a swollen slab shouldering its way out of the wood, nearly always within two metres of the ground and very often at the root flare of an ancient oak or on the lip of an old pruning wound.

Slow down before you touch anything. Note the tree species, the height on the trunk, whether the host is a living tree or a standing stump, and whether the bracket is pushing out of a crack, a wound or the buttress. That context does half the identification for you, because this species is tied to a very narrow set of hosts and positions.

Reading the shape and upper surface

The fruit body is tongue-shaped, spoon-shaped or broadly fan-shaped, usually 8 to 25 cm across, and unusually thick for a bracket at 2 to 6 cm through the middle. It attaches by a short, stout lateral stub rather than a proper stalk, and hangs or projects with a thick, rounded, paler margin.

Run a fingertip across the top. The surface is moist and slightly tacky, with a gelatinous outer skin, and it is covered in minute pimple-like papillae that give a distinctly rasping feel, closer to fine shagreen than to the smooth felt of most brackets. Colour runs from pinkish red and brick through to a dull maroon or blackish red in old specimens, often with faint radial streaking. Nothing else on a temperate trunk combines that colour with that texture.

The pore surface, and the character that settles it

Turn the bracket over, or crouch to look up at it. The underside is pale cream to pinkish yellow when fresh, ageing to dull ochre and staining reddish brown wherever you press it. Pores are round and moderately fine, roughly 2 to 3 per millimetre.

Now do the one test that closes the identification. Scrape the pore surface gently with a thumbnail, or slice a thin vertical section and look at the cut edge with a hand lens. In every other bracket you will meet, the tubes are fused into a single spongy layer. In Fistulina each tube is a separate free-standing cylinder, packed alongside its neighbours but not joined to them, so the surface behaves like a dense pile of tiny pipes and individual tubes rub away one at a time. The genus name means little pipes, and that is exactly what you are looking at.

Stipe, base and attachment

There is effectively no stipe. Expect a short, thick, lateral stub, sometimes so reduced that the bracket looks glued flat to the bark. Specimens emerging from a horizontal surface occasionally develop a rudimentary stalk a few centimetres long, but it is never slender and never central. If you are holding something with a well-formed central stalk, you are not holding this species.

Flesh and colour change on cutting

Cut the bracket vertically with a sharp blade and look at the section. The flesh is thick, soft and gelatinous-fibrous rather than corky, and it is radially streaked, so the section shows alternating pale and dark red bands like the grain in a polished stone. A thin, watery red juice seeps from the cut and stains the blade within seconds. Left exposed, the cut face darkens to a duller brownish red over several minutes. Old, weathered brackets dry much darker and tougher, losing the juice but keeping the streaked pattern in section.

Taking and reading a spore print

Cut a coin-sized piece of the pore surface with a thin layer of flesh behind it and lay it tube-side down on white paper or a glass slide. Cover it with a cup to hold humidity and leave it somewhere still for four to eight hours. A fresh, mature bracket drops spores freely.

The deposit is pale pinkish buff to a soft salmon brown. That colour is diagnostically useful in itself: most polypores you might confuse it with drop a plain white print, and Ganoderma species drop a cocoa brown one. Under a microscope the spores are small, smooth and broadly egg-shaped, roughly 4 to 6 by 3 to 4 micrometres, pale in water. Free tubes plus a pinkish buff print is a combination no other temperate bracket offers.

Substrate, host and season

This fungus is closely tied to oak (Quercus) and sweet chestnut (Castanea), with only occasional records from other broadleaves. It is annual, appearing from midsummer through late autumn, decaying quickly once frosts arrive, and it fruits singly or in small groups on the same trunk year after year.

Ecologically it is a brown-rot agent of heartwood. It works in the already-dead heartwood at the centre of a living tree rather than attacking living tissue, which is why the hosts are so often huge, healthy-looking veterans that stand for decades after the first bracket appears. The rot stains the timber a deep russet brown, a colouration timber workers know as brown oak. Finding this species is therefore a reliable sign of internal heart rot in an old tree, not of imminent collapse.

Separating it from its look-alikes

Ganoderma applanatum and G. australe sit in similar positions on similar trunks but are hard, woody and perennial, with a crusty brown upper surface, a white pore surface that bruises dark brown, tubes fused in stacked annual layers, and a cocoa-coloured spore deposit.

Inonotus dryadeus also favours the base of oaks, but forms a lumpy ochre-brown cushion that weeps amber droplets when young, and its flesh is fibrous rusty brown rather than marbled red, with no juice and no free tubes.

Laetiporus sulphureus is built in overlapping tiers, bright orange above with a sulphur-yellow margin, and its flesh is white and turns chalky with age, never red-streaked.

Meripilus giganteus forms a broad rosette of many thin fans at the base of beech, bruises blackish within minutes, and has far finer pores.

At a distance, red slime moulds such as Lycogala and Fuligo can briefly mimic the colour, but they are shapeless gelatinous cushions with no pores, no margin and no woody attachment.

Three-question field check

Oak or sweet chestnut, low on the trunk? Do the tubes on the underside separate individually under a thumbnail? Does a vertical cut show marbled flesh releasing a red juice? Three yeses is Fistulina hepatica.