Golden Scalycap

Pholiota aurivella is one of the largest and most colourful members of a genus of wood-inhabiting agarics in the Strophariaceae, all of which combine rusty-brown spore prints with veil remnants on cap or stipe. The genus name refers to the scaly cap surface typical of many species, and P. aurivella shows this in a distinctive form: its scales are flattened, dark rusty patches embedded in a layer of clear gluten.

The fungus is best known for fruiting high above the ground. Clusters commonly appear several metres up a trunk, sprouting from a pruning wound, a broken branch stub or a frost crack, which makes it one of the more conspicuous canopy fungi of autumn parkland and beechwoods. Fallen caps found at the foot of a tree are often the first clue that a colony is present overhead.

It belongs to a group of closely related golden scalycaps, including P. adiposa and P. limonella, which have been repeatedly redefined and are separated largely on spore size and the degree of glutinosity. Together they form the sticky-capped counterpart to the dry, shaggy P. squarrosa.

Cap

Large, 5-15 cm across, hemispherical then broadly convex to almost flat, sometimes with a slightly wavy margin. The ground colour is bright golden-yellow to rusty orange, and the surface is markedly viscid to glutinous when moist, drying shiny and tacky. Scattered across it are darker reddish-brown, flattened, gelatinous scales arranged in rough concentric zones; heavy rain can wash these off, leaving a nearly smooth slimy cap. The margin often carries hanging remnants of the pale veil when young.

Gills

Adnate, sometimes with a fine decurrent tooth, crowded and moderately broad. They begin pale straw-yellow, pass through olive-yellow and end deep rusty brown as the spores mature. The gill edge is usually a little paler and finely uneven.

Stipe

5-12 cm long and 1-2 cm thick, dry, firm and often strongly curved or eccentric because the fruit body grows sideways out of a trunk. Above the fibrillose ring zone it is pale yellow and smooth; below it is covered in recurved brownish fibrillose scales and darkens to rust-brown towards the base. The ring itself is a fibrillose band rather than a persistent membrane and is usually stained rusty with trapped spores.

Flesh & spore print

The flesh is firm and pale yellow, browning slowly in the stipe base, and does not blue or redden. The spore print is rusty brown; the spores are smooth, thick-walled and have a distinct germ pore, in contrast to the warty spores of Gymnopilus.

The Golden Scalycap is a fungus of broadleaf trees, particularly beech, elm, ash, poplar, willow and old orchard apples, with occasional records from conifers. It fruits from wounds, broken limbs, pruning cuts and dead sections of standing trunks, frequently well above head height, and also from stumps, fallen trunks and exposed roots. Clusters of several caps typically emerge from a single point of entry.

Fruiting runs from late summer through autumn, sometimes prolonged into early winter after mild weather. It is widespread across temperate Europe, northern Asia and North America, and is a familiar sight in parkland, avenues, mature beechwoods and hedgerow trees where old wounds are common. Colonies often reappear at the same wound for several successive seasons.

This species is both a wound parasite and a saprotroph. Spores germinate in exposed heartwood at broken branches and pruning cuts, and the mycelium spreads through the dead central column of the trunk, causing a white rot in which lignin and cellulose are both degraded and the residual wood becomes pale, soft and stringy. Once the tree dies the fungus continues to fruit from the standing snag or fallen trunk as a straightforward saprotroph.

By hollowing trunks from the inside it plays an important role in creating cavities used by hole-nesting birds, bats and invertebrates, and in accelerating the return of large woody debris to the soil. Its high-level fruiting position aids spore dispersal, releasing rusty spores into air currents well above the forest floor.

Pholiota adiposa is extremely similar and has often been confused with it; it tends to have a more persistently slimy cap with softer, less sharply defined scales, and reliable separation rests on smaller spores. Pholiota limonella is generally smaller and more lemon-yellow, again with smaller spores. Pholiota squarrosa is easily distinguished in the field because its cap is dry, not glutinous, and is covered with coarse, upright, pointed scales, and it typically fruits in large tufts at the base of trunks rather than high up.

Gymnopilus junonius shares the orange colouring and rusty spore print but has a dry, fibrillose cap without gelatinous scales, a persistent membranous ring, and grows in massive clusters at ground level. Honey fungus (Armillaria) can also erupt from trunk wounds but has cream to pinkish gills and a white spore print.