Field Blewit

The Field Blewit, widely known in rural England as Blue Leg, is a late-season grassland mushroom whose plain greyish-buff cap gives no hint of the vivid lilac-violet colour of its stipe. The contrast between drab cap and bright stem is the single most useful identification character, and it is why the fungus acquired so many regional names referring to blue legs.

It belongs to Lepista, a genus of fleshy, ringless agarics with sinuate to slightly decurrent gills and a pale pink spore print produced by minutely roughened spores. Its close relative Lepista nuda, the Wood Blewit, is violet throughout and grows in woodland litter, whereas L. saeva confines its violet colour to the stipe and lives in open turf.

The species is also listed under the synonym Lepista personata. It is one of the very last mushrooms of the year in many regions, often fruiting after the first frosts when almost nothing else remains in the grass.

Cap

The cap is 5-12 cm across, thick-fleshed, convex with an inrolled margin at first, becoming flat and finally slightly wavy or shallowly depressed. The surface is smooth, dry to slightly greasy in wet weather, and coloured pale greyish-buff, clay-brown or dull leather, sometimes with a faint violet flush at the extreme margin in very fresh specimens but usually plain.

Gills

The gills are crowded, fairly broad and sinuate to notched at the stipe, occasionally with a short decurrent tooth. They are whitish to pale buff, darkening to dull pinkish-buff as the spores mature, and they detach easily from the cap flesh.

Stipe

The stipe is the key feature: 3-8 cm long and 15-30 mm thick, stout, firm and often slightly swollen at the base, coloured bright lilac, violet or blue-purple and conspicuously streaked with darker longitudinal fibrils. The colour is strongest in fresh young specimens and fades to greyish-lilac in age or after frost. There is no ring and no volva.

Flesh and spore print

The flesh is thick, firm and white to pale lilac near the stipe apex, unchanging when cut, with a strong, pleasant, slightly perfumed smell. The spore print is pale pink to pinkish-buff, and the spores are minutely warty, which places it in Lepista rather than in the white-spored funnels.

The Field Blewit is a grassland species, growing in old permanent pasture, downland, meadow margins, grassy verges, churchyards and occasionally in well-manured arable field edges. It favours neutral to calcareous soils and is often associated with land that has been grazed for a long time.

It is a late fruiter, appearing from mid-autumn and frequently continuing into early winter after the first frosts have knocked back other fungi. Fruit bodies commonly come up in arcs, complete fairy rings or dense troops. The species is widespread across Europe and temperate Asia, with a scattered distribution in North America.

Lepista saeva is a saprotroph of grassland soils, decomposing grass thatch, dead roots and accumulated organic matter in the upper soil. It forms no partnership with tree roots, which is why it is a species of open turf rather than woodland.

The mycelium spreads outward through the sward and often produces visible fairy rings, sometimes accompanied by a band of darker green grass where nitrogen has been released. Because the mycelium is perennial, productive sites tend to fruit reliably year after year in the same rings, and the species' late season means it is often the final substantial mushroom to appear in a pasture before winter.

Lepista nuda, the Wood Blewit, is the closest relative and shares the pale pink spore print and sinuate gills, but its cap, gills and stipe are all violet to lilac when fresh, and it grows in woodland and hedgerow leaf litter and compost rather than open turf. Lepista sordida is smaller, thinner-fleshed and more uniformly lilac, often in nutrient-rich disturbed ground.

Cortinarius species with violet stipes can look superficially similar but have a cobwebby cortina over the young gills and a rusty-brown spore print that stains the stipe. Brown-capped grassland Entoloma species have truly pink, angular-spored gills and slender fibrous stipes without any violet colour, and lack the thick firm flesh of the Field Blewit.