Weeping Polypore

The Weeping Polypore is among the largest annual brackets found at the base of broadleaved trees, sometimes forming cushions half a metre or more across on the buttress roots of veteran oaks. Its common name comes from the remarkable habit of young, actively growing fruit bodies, which exude conspicuous amber to reddish-brown droplets from the upper surface and margin. These beads eventually dry to leave brown pits and stains across the top.

The species has long been placed in Inonotus and is still widely listed as Inonotus dryadeus, but it is now generally treated in the segregate genus Pseudoinonotus. Either way it belongs to the Hymenochaetaceae, the family of rusty-fleshed bracket fungi, and shares with its relatives a soft fibrous annual fruit body without a hard crust or lacquered surface.

It is a butt and root parasite of oak above all, and its appearance at the foot of a tree is a reliable outward sign that decay is under way in the root plate and lower trunk. It occurs throughout Europe, across temperate Asia and in North America wherever mature oaks grow, and it is a familiar find in ancient woodland, wood pasture and old parkland.

Fruit body

The bracket is large, commonly 10 to 40 cm across and occasionally much more, thick, heavy and cushion-like, and broadly attached to the trunk base or a buttress root. It may be solitary or several may fuse into an irregular mass along the root collar. Fresh specimens are strikingly heavy with retained water.

Upper surface

The top is uneven, lumpy and often coarsely warted or bumpy, finely velvety to almost bald, and whitish-buff to pale ochre or dull yellow-brown when young, darkening with age to rusty brown and finally blackish. The most striking feature of a young specimen is the abundant amber to reddish-brown droplets that stand on the surface and along the thick rounded margin, later drying to brown pits and stains.

Pores

The pore surface is whitish to pale cream or buff when fresh, bruising and ageing brown, and becomes dull rusty brown in old specimens. Pores are small and round, roughly 3 to 5 per millimetre, and the tubes are 1 to 3 cm deep.

Flesh and spore print

The flesh is rusty brown to tawny, soft, fibrous and moist when fresh, faintly zoned, and dries to a light, corky or crumbly mass. There is no hard crust. The spore deposit is whitish to very pale yellow.

This bracket is almost always found at the very base of a living tree, at ground level on the root collar, on exposed buttress roots or on the soil directly over a major root a short distance from the trunk. Oak is by far the most frequent tree, both in Europe and North America, with beech, sweet chestnut and occasionally other broadleaves also recorded, and there are reports from conifers such as fir in some regions.

Fruiting runs from summer into autumn, with the droplet-bearing young stage typically in mid to late summer. Old brackets blacken, harden and often persist at the tree base into the following year before collapsing. The species is widespread across Europe, temperate Asia and North America, and is most often encountered on mature and veteran trees in ancient woodland, wood pasture, parkland and older street and avenue plantings.

Pseudoinonotus dryadeus is a parasite of the roots and butt of living trees, causing a white rot in which lignin and cellulose are both degraded so that the affected wood becomes pale, soft and eventually spongy or hollow. Infection is centred on the root plate and lower trunk, and it can progress slowly over many years while the tree remains in full leaf above.

After the tree dies the fungus persists saprotrophically in the stump and root system. In woodland ecology, root and butt decay of this kind is a major driver of veteran tree structure, creating basal hollows and quantities of soft red-brown wood-mould that support specialist saproxylic beetles, other invertebrates and cavity-using vertebrates. The annual fruit body invests heavily in a thick water-rich structure that can sustain spore production over several weeks, with the exuded droplets thought to result from the high water flux of rapid growth.

Inonotus hispidus shares the rusty fibrous flesh but grows high on the trunks of ash, apple and walnut rather than at the base of oak, and has a genuinely shaggy, coarsely hairy upper surface with bright rusty orange fresh growth. Phaeolus schweinitzii also forms a large soft annual bracket near the tree base, but it is on conifers, has a densely velvety concentrically zoned top and greenish-yellow to olive pores that bruise dark brown.

Ganoderma applanatum and Ganoderma adspersum occupy similar positions at the trunk base but are perennial, with a hard grey-brown crust on top and a white pore surface that bruises brown instantly when scratched, plus stacked annual tube layers visible in section. Meripilus giganteus forms a rosette of many overlapping fan-shaped caps from a single base, with a whitish pore surface that blackens on handling, and lacks both rusty flesh and amber droplets.