Frayed Parasol

Macrolepiota excoriata is a grassland parasol built on a smaller and simpler plan than the towering woodland species. The name comes from the way the cap skin behaves as the mushroom expands: rather than breaking into neat concentric scales, the cuticle tears and pulls back from the rim in irregular flaps, so the margin looks scraped or frayed and the pale flesh shows through.

The species belongs to the Agaricaceae and displays the standard parasol characters - gills free from the stem, a white spore print, a membranous ring, and a cap cuticle distinct from the flesh beneath. Some authors move it to Leucoagaricus on molecular grounds, and both names appear in current literature.

It is above all a field mushroom. In short-grazed pasture, hay meadows and the grassy edges of arable land it appears as a scatter of pale, flat-topped caps a few centimetres above the turf, easily overlooked among grass but distinctive once the torn margin and unmarked stem are noticed.

Cap

5-10 cm across, ovoid then convex and finally flat or shallowly umbonate. The centre keeps a smooth, unbroken pale ochre to greyish-brown disc, while the surrounding surface is whitish to cream and thinly fibrillose. As the cap widens, the outer cuticle splits radially and lifts away in irregular ragged flaps and tatters, producing a frayed edge and sometimes a fringe of loose skin hanging beneath the margin.

Gills

Free from the stem, crowded, fairly broad, white to cream, occasionally with a faint pinkish or brownish tone in age. There is a distinct collar between the gill ends and the stem apex.

Stipe

5-10 cm tall and 6-12 mm thick, cylindrical, hollow, whitish to pale buff, smooth or very finely fibrillose with no dark banding, and slightly swollen or bulbous at the base. The ring is white, membranous and relatively simple, single-edged rather than elaborately double, and may become loose on the stem though it is less freely movable than in the large parasols.

Flesh & spore print

Flesh white, soft, and unchanging when cut, without the reddening seen in some relatives. The spore print is white and the spores are smooth, thick-walled ellipsoids with a germ pore and dextrinoid walls.

This is a species of open, grazed and mown grassland: pastures, hay meadows, downland, sports fields, dune grassland and the grassy margins of arable fields and tracks. It grows on soil among grass, often scattered or in small troops, and prefers well-drained, moderately fertile ground including calcareous and sandy soils. It is not tied to trees and rarely occurs under closed canopy.

The species is widespread through Europe, extending into western Asia and North Africa, with similar material reported from North America. Fruiting occurs from late summer into autumn, typically a few days after rain has soaked warm pasture, and colonies tend to return to the same fields year after year.

Macrolepiota excoriata is a grassland saprotroph. Its mycelium permeates the root thatch and upper soil, decomposing dead grass, roots and other humus, which frees nitrogen and minerals back into the sward. Grazed pasture suits it well because the constant return of dung and clippings keeps the humus layer rich while the short turf prevents shading.

Because it needs no fungal partnership with trees, it can colonise open landscapes far from woodland, and long-established colonies may spread outward through the soil in slowly expanding patches. The flat mature cap raised clear of the grass allows the white spores to fall freely into the airflow above the sward.

Macrolepiota mastoidea shares the pale colouring and grassland habitat but has a sharp nipple-like central papilla and a cap dressed with distinct small brown scales, with an intact rather than frayed margin. Macrolepiota procera is far larger, with coarse shaggy scales, a broad umbo and a stem heavily patterned in dark snakeskin bands.

Leucoagaricus leucothites, also a grassland species, has a smooth, silky, unbroken white cap with no torn margin, and its gills develop a pinkish tinge before ageing cream. Agaricus species of the same fields differ fundamentally in their gills, which turn from pink to chocolate brown, and in their dark brown spore print.