Lilac Fibrecap
Inocybe lilacina
Also called lilac inocybe, violet fibrecap
A small silky fibrecap washed with lilac to violet tones and topped by a pointed umbo, its gills maturing to dull clay-brown. Frequently found alongside its plain white counterpart.
Overview
Lilac Fibrecap is the violet-pigmented counterpart of the White Fibrecap, and for most of the twentieth century it was catalogued as Inocybe geophylla var. lilacina. Modern treatments generally raise it to species rank as Inocybe lilacina, recognising consistent differences in pigmentation and microscopic detail even though the two grow side by side.
It is a small, delicate, dry-capped agaric with the silky sheen typical of the genus. Fresh young caps carry a soft lilac to pale violet wash that is strongest at the margin, while the umbo often stays warmer and more ochre. The colour is fugitive: as the fruitbody ages and dries the violet drains away to leave a pale buff or cream cap, so mature specimens can be very hard to separate from ordinary White Fibrecap.
Among the many violet-toned woodland fungi it is the brown spore deposit that anchors the identification, placing it firmly with the fibrecaps rather than with the white-spored Laccaria and Mycena or the rusty-spored Cortinarius.
How to identify it
Cap
Small, 1–4 cm across, conical to bell-shaped when young and expanding to broadly convex with a persistent pointed umbo. The surface is dry, finely silky-fibrillose and lilac, violet-grey or pale amethyst when fresh, commonly with a yellowish or ochre-flushed umbo. Pigment fades quickly with age and dry weather, leaving cream to pale buff caps that retain only a hint of lilac at the extreme margin.
Gills
Adnexed, moderately crowded, pale lilac or greyish-lilac when very young, then passing through clay-buff to a dull brown as spores ripen. The edges stay paler and are minutely fringed. Loss of the violet gill tint with age is normal and does not indicate a different species.
Stipe
2–6 cm long, 2–5 mm thick, slender and cylindrical with a slightly swollen base that is not sharply rimmed. It is lilac-tinted along its length when fresh, particularly at the apex, fading to whitish-buff with age, and is finely silky-fibrillose. No ring is present, although fine veil threads may be visible near the apex on buttons.
Flesh and spore print
Flesh thin, whitish to faintly lilac, unchanging when cut. The odour is earthy to spermatic as in related fibrecaps. The spore print is snuff-brown; spores are smooth and almond-shaped, without nodules.
Where and when it grows
Lilac Fibrecap grows on soil in deciduous, mixed and coniferous woodland, favouring shaded path sides, banks, mossy verges and open litter beneath beech, oak, birch, hazel, pine and spruce. It tolerates a broad range of soil types and is frequent in planted amenity woodland, parks and shelterbelts as well as ancient woods.
Fruitbodies appear from midsummer through to late autumn, typically scattered or in loose troops, often intermixed with plain white plants of the closely related Inocybe geophylla. The species is widespread across Europe, northern Asia and temperate North America.
Ecological role
This species is ectomycorrhizal, forming nutrient-exchanging sheaths around the fine roots of a wide range of broadleaf and coniferous trees. The fungal partner extends a network of hyphae far beyond the reach of the root system, capturing nitrogen and phosphorus from litter and soil and passing them to the tree in exchange for sugars.
Its habit of fruiting along compacted path edges and around recently planted trees suggests a good tolerance of disturbance, and it is often among the first mycorrhizal fungi to colonise young plantations. The fruitbodies are ephemeral and are rapidly recycled by fungus gnats, mites and other litter invertebrates.
Similar species
The Amethyst Deceiver, Laccaria amethystina, is a much more saturated purple with thick, widely spaced, waxy-looking gills and a white spore print, whereas Lilac Fibrecap has crowded gills that turn brown. Mycena pura is pinkish-lilac with a smooth striate cap, a hollow brittle stipe, a radish-like odour and white spores.
Small violet Cortinarius species are separated by their cobwebby cortina between cap margin and stipe and by rusty-brown spore deposits that stain the stipe. Plain Inocybe geophylla has the same silhouette and texture but is pure white from the outset, never violet-flushed.