Turf Mottlegill

The Turf Mottlegill, Panaeolus fimicola, is a modest grey-brown agaric found where livestock have enriched the ground. The epithet fimicola means dung-dwelling, and although the fungus often fruits from grass rather than from a dung pat itself, it is closely tied to soil that has been manured.

It is a typical member of Panaeolus: thin-fleshed, dull-coloured, with a slender hollow stipe and gills that ripen unevenly to give the mottled appearance shared across the genus. The spore print is black, separating it from the superficially similar brown-spored Panaeolina.

The species has been treated under several names, including Panaeolus ater, and the boundaries between the smaller grey mottlegills remain debated. Field identification rests on the combination of habitat, small greyish hemispherical cap, mottled black gills and the absence of veil remnants on the cap margin.

Cap

The cap is small, 1 to 3 cm across, hemispherical to broadly convex and only rarely expanding fully. Colour is grey-brown to dull clay or slightly olive-tinged when moist, drying paler grey-buff, sometimes with a weak darker zone near the margin. The surface is smooth, dull and slightly greasy in wet weather, occasionally finely cracked over the disc in dry spells, and the margin is even and free of hanging veil teeth.

Gills

Gills are adnate, fairly broad and moderately spaced, pale grey at first, then progressively spotted and clouded with black as spores ripen unevenly. Mature gills appear marbled dark grey to black with narrow whitish edges, which contrast neatly against the darker faces.

Stipe

The stipe is slender and fragile, 3 to 8 cm long by 1 to 3 mm thick, straight, hollow and often finely pruinose or frosted toward the apex. Colour ranges from pale grey-brown to reddish brown, darkening at the base. There is no ring, no volva, and no bulb.

Flesh and spore print

The flesh is very thin and pallid grey-brown with no significant colour change on cutting or bruising. The spore print is black; the spores are smooth, thick-walled, lemon-shaped and furnished with a germ pore.

This mottlegill grows in grazed pasture, horse paddocks, manured lawns and grassy places enriched with animal droppings, and it also fruits directly from old dung of cattle, horses and sheep. It prefers open, sunny, well-fertilised turf and appears singly or in small scattered groups rather than in dense clusters.

The season is long, from spring through to late autumn, with flushes following rainfall in warm weather. It is widespread throughout Europe and occurs across temperate North America and in grazed grassland in many other parts of the world, its distribution effectively following that of pastured livestock.

Panaeolus fimicola is saprotrophic and coprophilous in tendency, digesting dung residues and the nitrogen-rich humus of manured soil. It forms no mycorrhizal partnership, and its mycelium is confined to the surface organic layer where droppings have been incorporated into the turf.

Dung fungi typically complete a rapid life cycle keyed to the availability of fresh substrate, and this species fruits soon after warm rain softens and wets manured ground. Spores released from the black gills settle on grass, may be ingested by grazing animals and pass through the gut to be deposited with fresh dung, a dispersal route that neatly explains the fungus's tight association with pasture.

Panaeolus papilionaceus grows in the same dunged pastures but is larger and more strongly bell-shaped, with conspicuous white toothed veil fragments fringing the cap margin, which the Turf Mottlegill lacks. Panaeolus cinctulus is bigger, warmer reddish-brown, has a much more pronounced dark marginal band when drying, and prefers compost and straw-enriched ground to raw pasture.

Panaeolina foenisecii overlaps in size and habitat but is browner overall and gives a dark brown spore print from warty spores, against the jet-black print and smooth spores here. Psathyrella species in grass are more brittle with paler, more flaring white stipes, and Deconica coprophila on dung has a distinctly viscid, more chestnut cap with a separable pellicle and a purplish-brown rather than black print.