Charcoal Scalycap

The Charcoal Scalycap is a strictly pyrophilous fungus, meaning it fruits only on ground that has been burnt. It is one of a small guild of specialists that colonise the charred, sterilised, alkaline soils left by bonfires, campfires, charcoal hearths and wildfires, and it can be locally abundant on such sites while being entirely absent from the surrounding woodland.

It is also known under the older name Pholiota carbonaria, and both epithets reflect the same striking habitat preference. Compared with its relatives such as the Golden and Alder Scalycaps it is a small, dull-coloured species, but its combination of a shiny viscid tawny cap, a finely scaly stipe and a burnt substrate makes it easy to place.

Within the genus it belongs to the sticky-capped group, and it sits ecologically alongside a distinctive post-fire succession of ascomycetes and agarics that appears in a fairly predictable order in the months and years after a fire.

Cap

Small, usually 2-5 cm across, convex then expanding to broadly convex or flat. The colour is a dull tawny, date-brown or foxy brown, generally darker in the centre and fading to a paler yellowish or olive-tinged margin. The surface is distinctly slimy or viscid when moist and dries to a smooth shine; fine pale veil fragments may cling to the young margin, but the cap itself is essentially smooth rather than scaly.

Gills

Adnate, crowded and moderately narrow, pale yellowish or buff at first, then dull clay-brown to olive-brown as spores mature. The gill edge is usually a shade paler and finely fringed.

Stipe

3-6 cm long and 3-6 mm thick, cylindrical, sometimes curved at the base. It is pale yellow at the apex and browns markedly downwards to rust or dark brown. Below an indistinct fibrillose ring zone the surface bears numerous small, recurved fibrillose scales that give a roughened texture, the feature responsible for the English name; above the zone the stipe is smooth.

Flesh & spore print

The flesh is pale yellow to buff, thin, and does not change colour on cutting. The odour is faint and unremarkable. The spore print is clay-brown to dull brown, and the spores are smooth and ellipsoid with a small germ pore.

The substrate requirement is unusually strict: this fungus grows on burnt ground. Typical sites are old bonfire patches in gardens and woodland clearings, campfire scars, charcoal-burning hearths, and areas of forest or heath that have carried a fire. The mycelium exploits charcoal, ash-enriched mineral soil and partly charred plant debris, and fruit bodies are frequently seen pushing directly through a crust of black charcoal fragments.

Fruiting can occur over a long season from spring through to late autumn, usually beginning some months after the burn and continuing for one to three years before the site is recolonised by ordinary vegetation and the fungus disappears. It is widespread across Europe, North America and other temperate regions, and its distribution simply follows the distribution of fires.

Pholiota highlandensis is a saprotroph adapted to the peculiar chemistry of post-fire soil. Burning sterilises the upper soil, destroys competing mycelia, raises the pH, and leaves behind charcoal and a flush of soluble mineral nutrients. Pyrophilous fungi such as this one survive as heat-resistant spores or resting structures and germinate into an environment with almost no competition, exploiting charred organic material and partially combusted plant remains.

The species is part of a well-documented succession. Cup fungi such as Pyronema and Anthracobia usually appear first within weeks of a fire, followed by agarics including this scalycap and later by species of Tephrocybe and Myxomphalia, before the burn scar is finally reclaimed by mosses, ordinary litter fungi and higher plants. In doing so these fungi stabilise the bare surface and begin rebuilding organic matter in the damaged soil.

Other fungi of burnt ground are the main sources of confusion. Myxomphalia maura has a dark greyish-brown, non-scaly cap, white decurrent gills and a white spore print, quite unlike the clay-brown gills and spores here. Tephrocybe anthracophila is greyish-brown, dry, and also drops white spores. Psathyrella pennata has a dry, silky-fibrillose greyish cap, a very fragile stipe and a dark blackish-brown spore print.

Among the scalycaps, Pholiota gummosa is paler and greener in tone and grows on buried wood in ordinary soil rather than burnt ground, while Pholiota alnicola is much brighter lemon-yellow and fruits in dense tufts on alder stumps. The combination of small size, viscid tawny cap, scaly lower stipe and a charcoal substrate is effectively diagnostic for the Charcoal Scalycap.