Goldenhaired Inkcap

The Goldenhaired Inkcap, Coprinellus xanthothrix, is a delicate member of the Psathyrellaceae and one of the many small inkcaps that appear on buried wood in gardens, parks and woodland. It belongs to the group of Coprinellus species whose caps are covered when young by a granular universal veil, and it takes its name from the warm golden-brown to tawny colour of those veil particles.

Like other inkcaps, its fruit bodies are short-lived. A young button expands over a few hours into an ovoid then bell-shaped cap, the gills darken from white through grey to black, and the cap margin then curls and dissolves into a dark liquid as the tissue autodigests. A troop of this species can therefore show every stage at once, from pale scurfy eggs to black tattered remnants.

The species is closely allied to the familiar Glistening Inkcap, Coprinellus micaceus, and separating the two reliably usually depends on the shape of the veil cells and the position of the spore germ pore, though the coarser, warmer-coloured veil granules of C. xanthothrix are often suggestive in the field.

Cap

The cap is 1 to 4 cm high and wide, at first egg-shaped or acorn-shaped, then bell-shaped and finally splitting and recurving at the margin. Ground colour is ochre to tawny brown, paler and greyer toward the striate edge, and the surface of young caps is coated in scattered golden-brown to rusty granules of universal veil that wash off in rain. Deep radial grooves run from the margin most of the way to the disc.

Gills

The gills are crowded, narrow and free or almost free from the stipe. They pass from white to greyish and then to black as the spores ripen, and in maturity they deliquesce, the whole cap margin melting upward into black ink-like drops.

Stipe

The stipe is white, hollow, fragile and finely silky or minutely mealy, typically 3 to 8 cm tall and only 2 to 5 mm thick. It has no ring and no volva, though the very base may be slightly swollen and attached to a mat of pale mycelium binding wood fragments and soil.

Flesh and spore print

The flesh is extremely thin, whitish, and shows no colour change on cutting. The spore print is black. Microscopically the veil is made of rounded to broadly elliptic thin-walled cells rather than the chains of more cylindrical cells found in some relatives, and the spores carry a central germ pore, a key technical character for the species.

This inkcap grows on and around buried and partly buried hardwood: old stumps, dead roots, buried planks, mulch and wood chips. It is common in gardens, hedge bottoms, parks, along path edges and in disturbed broadleaf woodland, often appearing to grow from bare soil when the wood source is entirely below ground. Beech, elm, ash, willow and poplar debris all suit it.

Fruiting is typically in tight clusters or loose troops of many caps, and can occur from spring right through to late autumn wherever there is warmth and moisture, often within a day or two of heavy rain. The species is widespread across Europe and has been reported from temperate North America and elsewhere, being much under-recorded because of its resemblance to other small inkcaps.

Coprinellus xanthothrix is saprotrophic, obtaining its nutrients by decomposing dead hardwood and woody litter. Its mycelium is a white-rot type coloniser of buried wood and root remains, and it plays a routine part in returning garden and woodland wood debris to the soil.

The deliquescent life cycle is highly compressed. Fruit bodies expand rapidly, mature spores over a matter of hours, and then autodigest from the cap margin inward, the receding edge exposing fresh spore-bearing gill surface and dripping spores away in dark fluid. This lets a very thin, crowded set of gills release its whole spore load without needing the durable structure of a longer-lived mushroom.

The nearest look-alike is the Glistening Inkcap, Coprinellus micaceus, which shares the ochre bell-shaped grooved cap, clustered habit on buried hardwood and black deliquescing gills. Its veil granules are usually finer, paler and more mica-like, glittering rather than golden and shaggy, and microscopically its veil cells are more elongated while the spore germ pore is slightly off-centre in some collections. Field separation is unreliable, and many records are aggregated under the C. micaceus group.

Coprinellus disseminatus forms far larger troops of much smaller, pale grey-buff, finely hairy caps, and its gills darken but scarcely dissolve. Coprinopsis lagopus is greyer, taller and clothed in whitish woolly fibrils rather than golden granules, with a thinner cap that collapses very quickly. Small Psathyrella species may look similar in colour and size but never deliquesce and have a duller dark brown rather than pure black print, with no granular veil on the cap.