Field Blewit Identification Guide

The field you are standing in

Lepista saeva is a fungus of old grassland, and the setting narrows the possibilities immediately. Think of unimproved permanent pasture, downland turf, a churchyard, a wide roadside verge, a village green or a hay meadow that has never been ploughed or heavily fertilised. The turf is short, the sward is species rich, and there may be waxcaps and earthtongues fruiting nearby.

The season is equally distinctive: this is a late fungus, appearing from mid autumn into early winter and continuing through the first frosts when almost everything else in the field has collapsed. Fruit bodies come up in troops, arcs and full rings that reappear in the same place year after year, and the grass inside a ring is often greener and longer.

The first impression is of a solid, pale, greyish-buff mushroom with a heavy stipe, sitting low in the grass with soil and grass blades stuck to the cap. It looks bulky and slightly nondescript until you look at the stipe, and then the violet appears.

Reading the cap

The cap is 6 to 12 cm across and sometimes reaches 15, thick fleshed and heavy in the hand. It is convex with an inrolled margin when young, expanding to flat or shallowly depressed, and the margin becomes wavy, lobed and irregular with age.

The surface is smooth and matt, faintly greasy when wet and silky when dry, and never scaly, hairy or slimy. The colour is a dull, unassertive pale greyish buff, clay, tan or pale mouse, sometimes with a faint pinkish or lilac flush right at the extreme margin in fresh young specimens but never the saturated violet of the woodland species. In dry spells the cap surface may crack into shallow plates, and it is usually spattered with soil.

Reading the gills

Turn the cap over. The gills are crowded, moderately broad, and sinuate, that is notched where they meet the stipe, which is an important structural point because it excludes the strongly decurrent grassland funnels.

Colour is pale buff, dirty cream or pinkish buff, deepening slightly with age, and crucially there is no violet or lilac in them at any stage. Push a thumb sideways across the gills: in this genus the whole gill trama separates cleanly from the cap flesh, peeling away as a layer, which is a genuinely useful confirmation.

Stipe, base and flesh

The stipe is the diagnostic feature and it is why people learn this species quickly. It is 3 to 7 cm long and a stout 1.5 to 3 cm thick, firm and solid, often slightly club shaped and swollen at the base. Over a paler ground it is clothed in longitudinal fibrils coloured a clear violet, lilac-blue or amethyst, strongest in young specimens and fading in old or weathered ones. Look at it under a lens in good light: the colour resolves into fine parallel fibres rather than a wash.

There is no ring, no cortina and no volva. The base is fastened into the turf by white mycelium bound around grass roots and soil, and it should be dug rather than pulled if you want to see it intact.

Cut the fruit body lengthways. The flesh is thick, firm and white to pale buff, sometimes with a lilac tint in the outer layer of the stipe just beneath the fibrils. It does not change colour on exposure beyond a slow dull browning in age. The smell is strong and distinctly perfumed.

Taking a spore print

This is the step that confirms the genus, and it must not be skipped when the stipe colour has faded. Take a fully open cap, cut the stipe off flush, place the cap gills down on white paper with a piece of black card beside it, cover with a bowl and leave four to eight hours in a cool place.

The deposit is pale pink to pinkish buff. It is pale enough that a thin print can be mistaken for cream, so scrape the powder into a heap with a blade and tilt it against the light before deciding. Under a microscope the spores are ellipsoid, roughly 6 to 9 by 4 to 5 microns, and finely warted, giving a granular outline at high magnification. A pale pink print plus roughened spores places a fungus in Lepista and separates it from the smooth-spored, white-printed funnels.

Substrate and season

The fungus is saprotrophic, breaking down accumulated grass litter and thatch in undisturbed swards, so it needs continuity rather than a particular tree. Ploughing, reseeding and heavy fertiliser destroy the colonies, which is why old pasture, verges and churchyards are the productive places. Fruiting is late, typically from October into December, and it tolerates frost that finishes most other grassland fungi.

Separating it from look-alikes

Lepista nuda, the Wood Blewit, is the closest relative. It is violet throughout when fresh, with a lilac cap and, decisively, lilac gills, and it grows in woodland litter, hedge banks and compost heaps rather than open turf. Faded specimens can look confusingly pale, but they retain lilac tones in the gills, whereas Lepista saeva never has violet gills at any age.

Lepista irina is a pale grassland and woodland species of similar build with a strongly perfumed smell and a pinkish print, but its stipe is plain whitish with no trace of violet fibrils.

Lepista panaeolus, sometimes called Lepista luscina, shares the same fields. Its cap is greyish with concentric darker water spots, its gills are greyish, and the stipe again lacks violet.

Clitocybe nebularis is bulky and grey capped but has decurrent gills that run down the stipe, a whitish to pale cream spore print, and a woodland habitat.

Entoloma species can approach the colour and build, but their spore print is a stronger salmon pink, their spores are angular in profile, and they never show violet stipe fibrils.

Cortinarius species with lilac tints are ruled out by the cobwebby veil remnants on the stipe and by a rusty brown spore print, and Tricholoma species by a plain white print. When in doubt, the print settles it.