Weeping Polypore Identification Guide

The Moment You Spot It

You almost never find this fungus by scanning the canopy. You find it by looking down. The Weeping Polypore is a ground-level fungus of big, old, open-grown oaks: park trees, hedgerow veterans, avenue trees with mown grass running right up to the trunk. Walk a slow circuit of the buttress roots and, in late summer, you will see what looks like a slab of dirty putty or a half-buried loaf shoved out between two root flares. It is broadly attached, sessile, and often sits partly on the soil surface, with grass blades and leaf litter fused into its margin.

Size registers first. A single bracket can be 10 to 40 cm across and 5 to 15 cm thick, and clusters running along a root flare can span most of a metre. The shape is cushion-like rather than shelf-like: thick at the attachment, tapering to a rounded, blunt, slightly inrolled margin. Nothing about it is elegant. It looks lumpy, swollen and heavy, and if you press it while fresh it gives like damp cork.

Reading the Upper Surface

Get down to eye level with the top of the bracket. Fresh growth is pale: buff, ochre, dull cream or a faintly pinkish tan, with a paler, almost white growing edge. The surface is uneven and tuberculate, often furrowed, with shallow pits and low bumps rather than a smooth skin. It feels finely velvety to the fingertip when young, not hairy or shaggy.

Age changes it completely. By autumn the same bracket has gone rusty brown, then dark umber, and finally near-black and crusted, with radial cracks and a matted, dirt-caked look. Old specimens harden in place through the winter and can still be named in spring by their position on the root flare and by the colour of the interior. If you find a blackened lump at the base of an oak and cannot decide what it is, the section will tell you.

The Weeping and the Pore Surface

The name is literal, and it gives you the best single character. Actively growing brackets exude clear to amber or rusty-brown droplets from the underside and margin, sometimes so freely that liquid runs down the bark and pools on the soil beneath. In warm, humid weather in July and August the droplets bead across the whole pore surface like condensation on a cold glass. As they dry they leave dark reddish-brown stains and pit-marks on the underside, and those stains persist long after the weeping stops. They alone are diagnostic once you know to look for them.

Underneath, tilt a torch across the surface at a low angle. The pores are small and round, roughly four to six per millimetre, so the surface reads as fine and suede-like rather than obviously perforated. Colour runs whitish to cream or pale grey when young, discolouring to dull ochre and then brown with handling and age. Press a thumb into a fresh pore surface and the bruise darkens to brown within a minute or two. The tube layer is shallow, usually under 15 mm, and sits as a distinct band above the flesh.

Flesh, Section and Colour

Cut the bracket vertically with a strong knife; the flesh is fibrous and tough enough to blunt a small blade. What you want to see is the contrast in section. The flesh is rusty brown to cinnamon or tobacco brown, soft-fibrous, sometimes faintly zoned in concentric bands, and it may show a silky sheen when torn along the grain. Near the upper surface there is often a slightly denser, darker crust; below the flesh sits the paler tube layer. Rusty-brown flesh with a paler pore layer is the combination to fix in memory. There is no dramatic reaction on cutting: the flesh stays brown, though the cut face darkens a little as it dries.

Stipe and Attachment

There is no stipe at all. The fungus is sessile and broadly attached, growing directly out of a root, the root collar or the lowest half-metre of trunk, and it frequently develops half-buried in soil or litter so that the point of attachment is hidden. Excavate gently behind the bracket and you will normally find it emerging from wood rather than from soil, which separates it at once from any terrestrial polypore.

Spore Print

Because the fungus is sessile and often sitting on soil, the practical method is to cut a wedge that includes a clean strip of pore surface, lay it pore-side down on dark paper or glass, cover it with a bowl to hold humidity, and leave it overnight somewhere cool. The deposit is white to very pale yellowish or straw-tinted, and it can be thin, so give it a full night. Do not let the rusty-brown flesh and the brown droplet stains fool you into expecting a brown print. A pale print from a bracket with rusty-brown flesh growing on oak roots is a powerful combination. Under a lens the spores are broadly ellipsoid to subglobose, smooth and nearly colourless.

Substrate, Host and Season

The habitat is narrow, and it does much of the identification work for you. This is an oak specialist across Europe and North America, recorded occasionally on beech, elm, maple, sweet chestnut and a handful of other broadleaves, and it is essentially confined to the root plate, buttress roots and lower trunk. It decays the butt and roots of living trees, working from the inside outward, so the host is usually a large mature specimen that still looks full in the crown. Fresh brackets appear from June to September, weep through the warm weeks, then blacken and persist as hard remnants into the following spring. The brackets are annual, not perennial, so you will often see this year's pale cushion sitting beside last year's black crust.

Separating It from Look-alikes

Shaggy Bracket (Inonotus hispidus) shares the rusty-brown flesh and the habit of weeping, but it grows high on the trunk of ash, apple and plane rather than at the base of oak, and its upper surface is coarsely and unmistakably hairy, like wet felt or a doormat.

Inonotus cuticularis is thinner and more shelf-like, often tiered, and typically on beech at some height, with a hairy to matted cap surface; it never forms the thick basal cushion of the Weeping Polypore.

Ganoderma species occupy the same root-flare position but have a hard, often varnished crust you can rap with a knuckle, a white pore surface bruising chocolate brown, thick perennial tube layers stacked in section, and a rain of cocoa-coloured spore dust settling on the bark above them. The Weeping Polypore is soft, annual and pale-printed.

Meripilus giganteus, also a root fungus of broadleaves, forms a rosette of many overlapping fan-shaped caps arising from a common base, with paler, pliable flesh that blackens dramatically where handled. The Weeping Polypore is a single thick cushion and does not blacken on touch.

Phaeolus schweinitzii has similar rusty-brown flesh but grows at the base of conifers, is often stalked and velvety with a bright sulphur-yellow margin, and its pore surface is large-pored, angular and maze-like.

Fistulina hepatica, another oak-base bracket, is soft, wet and liver-coloured, with tubes that separate as individual tubelets and flesh marbled with reddish streaks; one cut settles it.