Bonfire Scalycap

The Bonfire Scalycap is one of the classic pyrophilous, or fire-loving, fungi: it appears almost exclusively on burnt ground — old campfire sites, charcoal patches, burnt stumps and the scorched soil left after forest fires or heath burning — and is rarely if ever found away from them. Where a bonfire has stood for a season or two, small groups of tawny caps often push straight through the black crust of charcoal.

The species belongs to Pholiota, the rusty-spored, scaly, wood- and litter-inhabiting genus in the Strophariaceae, but it is one of the smaller and least scaly members: its cap is smooth and sticky rather than shaggy, with veil remnants restricted mainly to the margin. It has long been known under the name Pholiota carbonaria, a reference to charcoal, and both names are in wide use.

Its habitat specificity makes it easy to place. A small brown-spored mushroom with a viscid two-toned cap growing directly on charcoal in an old fire scar is very likely this species or one of a small handful of companions in the burn-site community.

Cap

The cap is 2–5 cm across, convex at first and expanding to broadly convex or nearly flat. The surface is distinctly viscid to glutinous when moist and shining when dry, coloured a warm tawny, rusty or dark reddish-brown over the centre and grading to a paler yellowish-ochre or olive-yellow at the margin. Fine whitish veil remnants often adhere to the cap edge in young specimens, but there are no coarse upturned scales on the cap disc.

Gills

The gills are adnate to slightly decurrent by a tooth, crowded and rather narrow, pale yellowish or clay-coloured when young and darkening steadily to dull cinnamon or greyish-brown as the spores ripen. In some collections the maturing gills take on a faintly olive cast.

Stipe

The stipe is 3–6 cm long and 3–8 mm thick, equal or slightly tapering, often curved as it emerges from an uneven charcoal surface. It is pale yellowish and smooth above, and browner below where it is covered with small fibrillose scales or fibrillose bands. A faint fibrillose ring zone marks the position of the veil, and it is often dusted brown by fallen spores. The base is frequently stained blackish by contact with charcoal.

Flesh and spore print

The flesh is pale yellowish to brownish, thin, without a distinctive odour. The spore print is brown to rusty brown.

The Bonfire Scalycap fruits on burnt substrates: charred soil, charcoal, ash beds, burnt stumps and logs, and the scorched litter layer of fire-affected ground. Old campfire and bonfire sites, charcoal-burning platforms, and areas subject to heathland or forest fire are the reliable places to look, and it is generally absent from unburnt ground nearby.

It appears in the seasons following a fire — typically from the first year after burning and often persisting for two or three years while the charcoal layer remains — then declines as vegetation recolonises. Fruiting bodies grow scattered or in small gregarious groups. The species is widespread in the northern hemisphere, recorded across Europe, North America and temperate Asia wherever fire creates suitable ground.

This is a saprotroph of the specialised post-fire community. Burning sterilises the upper soil, destroys competing mycelia, alters pH sharply upwards and leaves behind charcoal and partially pyrolysed organic matter — an unusual substrate that few fungi can exploit. Pyrophilous species such as this one are adapted to germinate and grow under exactly those conditions, and their spores or resistant propagules can lie dormant in soil for long periods until a fire creates the opening.

The post-fire succession is fairly consistent: cup fungi and small ascomycetes typically appear first, followed by pyrophilous gilled fungi including this species, with the community fading over a few years as ordinary soil fungi and plants return. In this sequence the Bonfire Scalycap helps process charred organic matter and stabilise the burnt surface, contributing to the early recovery of soil structure and nutrient cycling after fire.

Myxomphalia maura shares the burnt-ground habitat and is similar in size, but has a dark grey-brown cap with a depressed centre, distinctly decurrent whitish gills and a white spore print rather than brown. Tephrocybe anthracophila is another burn-site species, but is grey-brown, dry-capped and white-spored. Psathyrella pennata also fruits on charcoal but has a dry, fibrillose greyish-brown cap, very brittle flesh, and a dark blackish-brown spore print.

Other Pholiota species that may occur near burnt wood are generally larger and more conspicuously scaly, with dry shaggy caps rather than the smooth viscid surface of the Bonfire Scalycap, and they fruit on wood rather than on charred soil.