Mousepee Pinkgill

The Mousepee Pinkgill is one of the most unmistakable small fungi of old grassland. While its cap is a modest olive-brown, its slender stipe glows a clear blue-green or verdigris that intensifies where handled, a colour scheme shared by almost nothing else in the turf.

The blunt English name records its smell, a pungent, sour, mouse-like odour that many people find easier to notice than to describe. Together with the green pigmentation and the pink spore print, this makes the species identifiable at a glance.

It belongs to Entoloma section Leptonia, a group of small, often brightly coloured, slender-stiped species of unimproved grassland and heath, several of which show blue or violet tones.

Cap

The cap is small, 1-3.5 cm across, convex then flattened and typically depressed or umbilicate at the centre. Colour is olive-brown to yellow-brown or dull green-brown, often with greener tones near the margin, and the surface is finely fibrillose to slightly scurfy at the disc and translucent-striate towards the edge when moist.

Gills

Gills are adnate with a decurrent tooth, fairly widely spaced, and pale greenish to yellowish-white at first, becoming pink and finally salmon as the spores mature. Gill edges are even.

Stipe

The stipe is the signature feature: 2-6 cm tall, slender, hollow, smooth and bright blue-green, verdigris or grass-green, sometimes yellower above and greener below, bruising darker blue-green wherever touched. The base bears white mycelial down. No ring, no volva.

Flesh and spore print

The flesh is thin and greenish, discolouring blue-green where cut or bruised. The smell is strong and mouse-like or sour. The spore print is pink, with the usual angular Entoloma spores.

This species grows in short, unimproved grassland, showing a marked preference for calcareous ground: chalk and limestone downland, base-rich pasture, coastal turf over shell sand, dune grassland and old churchyards. It grows among mosses in closely grazed or mown swards and often appears alongside waxcaps and earthtongues.

Fruiting runs from summer into autumn. The species is widespread but local across Europe, with strongholds on unimproved calcareous grassland, and it is also recorded from parts of North America. Fruitbodies are usually scattered singly or in small groups and are easy to overlook because of their small size.

Entoloma incanum is a grassland species associated with long-established, nutrient-poor turf. The nutritional strategy of section Leptonia is not fully resolved: some evidence points to saprotrophy in the moss and root layer, while other work suggests a biotrophic link with grassland plants or bryophytes, and the group behaves ecologically much like the waxcaps it accompanies.

Whatever the precise mechanism, the fungus is intolerant of ploughing, reseeding and fertiliser and is treated as an indicator species in grassland fungus surveys. Its mycelium persists for many years in undisturbed turf, fruiting after summer and autumn rainfall.

No other common grassland fungus combines an olive-brown umbilicate cap with a bright verdigris stipe, so confusion is limited. Other blue-toned Entoloma such as the Blue Edge Pinkgill (Entoloma serrulatum) have dark blue-black caps and blue-black serrated gill edges, and their stipes are blue rather than green.

The Parrot Waxcap (Gliophorus psittacinus) also shows green tones, but its cap and stipe are conspicuously slimy, its gills are thick and waxy, and it gives a white spore print. Small green-tinged Leptonia relatives such as Entoloma chalybaeum are blue-violet overall without the greenish flesh or the mouse-like smell.