Amethyst Deceiver Identification Guide

First Impression and Setting

The Amethyst Deceiver is one of the easiest woodland mushrooms to spot and one of the easiest to misjudge, and both facts come from the same source: colour. In good condition it is an unmistakable violet — cap, gills and stalk all a deep amethyst purple — glowing against brown leaf litter. In poor condition it has faded to a washed-out buff and looks like nothing in particular. The second half of its name refers precisely to that habit.

Expect to find it in damp deciduous woodland, especially under beech and oak, and also in mixed and coniferous woods. It favours mossy banks, path edges, the shaded litter of old woodland and the sides of ditches. It is mycorrhizal, so it appears where tree roots are, generally scattered in loose troops of a dozen or more rather than singly, from late summer through to the first hard frosts. It is common and widespread across Europe and North America; in western North America the related Laccaria amethysteo-occidentalis takes its place, and in eastern woods the larger Laccaria ochropurpurea occurs.

Reading the Cap

The cap is small, 1 to 6 cm across. It starts convex, flattens, and then often becomes shallowly depressed or umbilicate at the centre, with a wavy, scalloped or irregularly lobed margin in older specimens.

Colour depends entirely on hydration. Fresh and moist, it is deep lilac to violet-purple throughout; as it dries, colour drains from the centre outward and it becomes pale lilac-grey, greyish-ochre, buff or nearly white. This hygrophanous fading is normal, not decay, and a single troop may contain specimens at every stage.

Feel and inspect the surface with a lens. It is not smooth or shiny. It is finely scurfy, minutely scaly or roughened, with a slightly granular look, and when saturated the margin is translucent-striate so that the gill positions show through as fine radial lines.

The Gills

The gills are the most useful character on the whole mushroom and the one that survives the fading. They are thick, broad, waxy-looking and distinctly widely spaced — you can count them easily by eye — with shorter gills interspersed. Attachment is adnate to slightly decurrent, running a short distance onto the stalk.

Their colour is deep violet and it holds much longer than the cap colour, so a mushroom whose cap has bleached to pale buff will very often still show clearly purple gills. On mature specimens the gill faces are dusted with a whitish bloom of shed spores over the violet ground; that pale frosting on violet gills is a strong field confirmation.

Stipe, Base and Flesh

The stipe is 3 to 10 cm long and only 2 to 8 mm thick, so it looks disproportionately long and thin for the cap. It is coloured like the cap, violet fading to lilac-buff, and it is distinctly fibrous and tough — you can twist it rather than snap it cleanly.

Look along its length: it is longitudinally fibrillose, with fine pale fibres running the length, and it is often flattened, grooved or slightly twisted rather than perfectly round. It is stuffed then hollow. Excavate the base and you should find a covering of lilac to whitish woolly mycelium binding leaf fragments, soil crumbs and moss into a small clump.

Slice the fruitbody. The flesh is thin, watery, and violet-tinged, concolorous with the surface. Nothing happens on cutting: no latex, no milk, no colour change, no darkening at the base.

Taking a Spore Print

Because the cap is small, take a print from two or three mature caps at once. Cut the stipes flush, set the caps gills-down on white paper with a dark card or glass slide under part of the group, cover with a bowl and leave them for several hours or overnight.

The print is white — and this is where the deceiving stops. Every purple-capped mushroom that could reasonably confuse you falls into a different spore-colour group. If you have a microscope you get an extra confirmation: the spores are almost perfectly globose, 8 to 10 micrometres in diameter, and covered in conspicuous long spines, sometimes 1 to 2 micrometres in length. Spiny round spores plus a white print is definitive for the genus.

Substrate and Season

The substrate is soil and leaf litter beneath living trees, not wood. Damp, shaded, humus-rich ground under beech is the classic, but oak, birch, and conifers all host it. Season runs from midsummer to late autumn, extending through mild spells into early winter, and it is one of the fungi that reliably persists after the main autumn flush is over.

Separating It From Look-Alikes

Laccaria laccata has the same build, texture, thick spaced gills, fibrous stipe and white spiny spores, but is pinkish-brown, brick or orange-tan. Faded amethystina can approach it, so check the gills: even a badly faded Amethyst Deceiver keeps lilac tones in the gills, whereas L. laccata gills are pinkish-flesh coloured.

Mycena pura is lilac to pinkish-lilac and grows in the same litter, but its cap is smooth and bell-shaped, its gills are close, thin and pale pinkish-white rather than thick, spaced and violet, and its stipe is smooth, cartilaginous and hollow. It has a strong radish-like smell.

Cortinarius species, including the deeply violet Cortinarius violaceus and the purple-tinged C. purpurascens, are larger and fleshier, show a cobwebby cortina between cap margin and stipe when young, and mature to rusty-brown gills with rust-coloured dust caught on the stalk. Their spore print is rusty brown.

Inocybe geophylla var. lilacina is pale lilac but has a conical, silky-fibrillose cap with a pointed umbo, crowded gills that become dull clay-brown, a mealy smell, and a dull brown spore print.

Lepista nuda is far larger and thicker-fleshed, with a smooth bluish-lilac cap, crowded gills, and a pale pinkish spore print.

Field Checklist

Small violet mushroom in damp broadleaf litter; scurfy cap fading to buff from the centre; thick, widely spaced violet gills often frosted white with spores; long fibrous twisted violet stipe with lilac woolly mycelium at the base; no colour change on cutting; white spore print of round spiny spores.