Hoof Fungus Identification Guide

The Silhouette You Learn First

Hoof Fungus is one of the few fungi you can name from thirty paces. Walking a birch wood, you notice a grey shape on a standing dead trunk that looks exactly like a horse's hoof pressed against the bark: broadly attached above, curving out and down to a blunt rounded rim, with the whole thing tilted so that the underside faces the ground.

It is a perennial, so unlike most fungi you will find it in every month of the year, and the same bracket will still be there next year and the year after, a little larger each time. Old individuals reach 30 to 45 cm across and can weigh several kilograms. Dead standing birch trunks are the classic setting, along with beech in some regions, and you will frequently find a whole ladder of brackets stacked up one trunk.

Reading the Upper Surface

Get your hand on it. The upper surface is covered by a hard, tough crust, a genuine rind rather than a skin, that feels like dense wood or old leather and cannot be dented with a thumbnail. Colour runs from pale ash-grey and silver-grey to brownish-grey, darkening with age until the oldest parts near the attachment are almost black, while the growing margin is often paler, buff or faintly ochre.

The surface is arranged in concentric zones, each a broad, slightly stepped band marking a season's growth, separated by shallow grooves. Reading those bands from the attachment point outward gives you a rough age for the bracket. The crust is usually smooth but often becomes cracked, scarred or moss-grown on very old individuals.

The profile is important. Look at the bracket side-on: a true hoof shape, thickest where it joins the tree, with a strongly convex upper surface and a broad rounded margin. It is not a flat shelf and it is not a thin fan.

Reading the Pore Surface

Turn your head and look underneath. The pore surface is flat to slightly convex, pale greyish-brown, coffee-with-milk brown or dull ochre-brown, and it darkens where you scratch it, a scratched line showing as a slightly darker brown mark rather than a strong colour reaction.

Put a lens on it. The pores are round, regular and small: roughly 2 to 4 per millimetre, evenly spaced across the entire fertile face. There are no gills, no teeth and no maze-like slots. The margin around the pore field is sterile, narrow and paler.

Cutting Through It

This is the test that clinches the species, and it needs a strong knife or a small saw. Cut vertically through the bracket from the top edge to the pore surface. Three layers should appear.

First, the hard outer crust, a few millimetres thick and sharply demarcated from what lies beneath.

Second, the context: a thick, soft, fibrous layer that is warm cinnamon to yellow-brown and has an extraordinary texture, felty and suede-like, so that you can peel and stretch it in sheets. It compresses under the thumb like dense felt and springs back only slowly. This soft brown layer under a stony crust is unlike anything else on the same trees, and it is the origin of the traditional name amadou for the material.

Third, the tube layers. Because the bracket is perennial, each year's tubes are added below the last, and in section you see a stack of distinct strata, often separated by thin lines of paler context tissue. Counting these layers is another way to age the specimen, and old brackets can show a dozen or more. The tubes themselves are rusty brown and the layer is denser than the felty context above it.

Colour Change and Odour

Cut surfaces darken slowly on exposure but do not flash red, blue or black. Fresh growing margins may weep a little clear moisture in damp weather. The odour is faint and slightly acidic or fruity in young growing brackets and essentially absent in old ones; it is not a useful separator.

Getting a Spore Deposit

Brackets are awkward to print because you cannot invert them conveniently, but there are two approaches. The first is to look for a natural print: in spring, when this species releases spores in enormous quantities, you will often see a fine whitish bloom dusting the upper surface of brackets growing below, or on the bark and leaves beneath a large individual. That white dust is the spore deposit and is easy to spot on a dark trunk.

The second is to cut a small wedge that includes an intact patch of pore surface, prop it pore-side down over dark paper in a covered container, and leave it overnight in a humid space. Fresh material gives a white to very pale cream print. Microscopically the spores are large, smooth, thin-walled and cylindric to narrowly ellipsoid, in the region of 15 to 20 by 5 to 6 micrometres, long sausage-shaped spores that are distinctive in their own right.

Substrate and Season

The fungus is a wood decayer of hardwoods, overwhelmingly birch across much of its northern range and beech further south, with occasional records on poplar, sycamore, maple, alder and willow. It fruits from standing dead trunks, large fallen logs and dying limbs on still-living trees, always from the wood itself rather than from soil.

Being perennial, the bracket is present year-round. New growth is added in a flush during the warmer months, when the margin is pale and slightly velvety; spore release is heaviest in spring.

Sorting Out the Look-Alikes

Red-Belted Bracket (Fomitopsis pinicola) is similar in hardness and habit but usually shows a resinous, lacquered band of orange-red or reddish-brown just inside the pale margin, has a whitish to pale cream pore surface and a pale cream context rather than a brown one, and grows mostly on conifers.

Willow Bracket (Phellinus igniarius) is also hoof-shaped, but its upper crust is much harder, darker and cracked into a blocky grey-black mosaic, the context is dense, woody and rusty-brown rather than soft and felty, and the whole bracket is heavier for its size. It favours willow and poplar.

Artist's Bracket (Ganoderma applanatum) is a flat shelf rather than a hoof, with a lumpy grey-brown upper surface, a white pore surface that instantly bruises dark brown when you scratch it, and a cocoa-brown context flecked with white pockets.

Birch Polypore (Fomitopsis betulina) shares the birch substrate but is annual, kidney-shaped and smooth, with a thin pale brown skin, a strongly inrolled margin, a white pore surface, and a soft, corky white interior throughout.

Other Phellinus and Fomitiporia brackets are separated by their rusty-brown, woody context, much smaller pores, and the absence of any felty layer.

Field Checklist

Hoof-shaped, broadly attached, perennial; hard concentrically zoned grey crust; small round pale brown pores at 2 to 4 per mm; soft felty cinnamon-brown context beneath the crust; multiple stacked tube layers in section; white spore deposit; on standing dead birch or beech; present all year.