Pink Domecap

The Pink Domecap (Calocybe carnea) is a small, tidy, brightly coloured grassland fungus. Calocybe is a modest genus of fleshy white-spored agarics with crowded gills and firm flesh, best known for the spring-fruiting St George's Mushroom; carnea means flesh-coloured, describing the soft rose to brick-pink of the cap and stipe.

The striking feature is the colour contrast. The cap and stipe are a clear pink, while the closely packed gills are pure white to cream, so the fruitbody looks as if it has been dipped in colour with the gills left untouched. At only a few centimetres across, it is easily overlooked in longer grass, but it stands out clearly on mown lawns and mossy short turf.

Grassland fungi with pink tones are a small group, and most of them are pink-spored Entoloma species. Taking a spore print therefore does most of the identification work: a white deposit under a pink-capped, white-gilled lawn mushroom points firmly to Calocybe carnea.

Cap

1.5 to 4 cm across, hemispherical to convex and retaining a neat domed profile for a long time, eventually flattening slightly. The surface is smooth, dry and matt to faintly silky, rose-pink to brick or salmon pink, sometimes fading to buff-pink in dry weather. The margin is even and often slightly inrolled when young.

Gills

White to cream, remaining pale, very crowded and rather narrow, with an adnexed to sinuate attachment. Numerous short intermediate gills are present between the full-length ones.

Stipe

2 to 5 cm tall and only 2 to 5 mm thick, cylindrical, often slightly curved, coloured like the cap in pink to brownish-pink tones and finely silky-fibrillose. It is stuffed then hollow, with a whitish downy base and no ring or volva.

Flesh & spore print

The flesh is white to very pale pinkish, thin and firm, with no colour change when cut. Odour is faint and not distinctive. The spore print is white, and the spores are small, smooth and ellipsoid — not angular as in the pink-spored genera.

This is a species of short grassland: mown lawns, churchyards, park turf, roadside verges, dune grassland and mossy pasture. It favours unfertilised, moss-rich turf and often appears alongside waxcaps and other grassland fungi in old undisturbed swards, though it also tolerates more ordinary garden lawns.

Fruiting is broad, running from early summer through to late autumn, with flushes following rain. It usually appears scattered or in small groups rather than large troops. The species is widespread across Europe and reported from temperate North America and Asia.

Calocybe carnea is saprotrophic, decomposing the accumulated dead grass roots, thatch and moss litter in the upper layers of turf. Its mycelium spreads through this organic mat, breaking down cellulose and lignified plant remains and recycling nutrients back into the soil, which is why it is associated with turf that has been left unimproved rather than with living tree roots.

Because it depends on undisturbed organic matter in the sward, it is a useful component of the grassland fungus assemblage that also includes waxcaps, earthtongues and pinkgills. Heavy fertilising, ploughing or reseeding removes the fine organic layer these fungi need, and the species disappears from such sites.

Calocybe gambosa, the St George's Mushroom, is a much larger, thick-fleshed white to cream species fruiting in spring with a strong farinaceous odour, and lacks any pink pigment. Pink-capped Entoloma species in the same turf are separated by their salmon-pink spore print and angular spores, and their gills usually turn pink as the spores mature rather than staying white.

Laccaria laccata shares grassy and woodland-edge habitats and can look pinkish, but its cap is more orange-brown, its gills are thick, widely spaced and distinctly pinkish, and its stipe is tough and fibrous. Mycena pura is larger, lilac-pink rather than rose, has a strongly radish-like smell and a taller fragile stipe, and grows mainly in woodland litter. Rhodocybe species have dull pinkish-brown caps and pinkish spore deposits.