Violet Fairy Cup Identification Guide

The Setting Does Half the Work

Violet Fairy Cup is one of a small group of fungi that you look for by looking for burnt ground rather than by looking for fungi. The classic find is on the blackened patch left by a campfire a season or two earlier, on a heath after a controlled burn, on the charcoal scatter where a brash pile was burned in a plantation, or along the scorched edge of a track. Bare, compacted, charcoal-flecked soil with almost no competing vegetation is the habitat, and in spring and early summer it can be carpeted with small cups.

The first impression is of scattered lilac buttons pressed into black soil, a few millimetres to a couple of centimetres across, often in loose colonies of dozens. Against charcoal the colour reads as a soft violet or purple-grey, not the vivid amethyst of a coral fungus. Many finds are made by kicking over an old fire ring; if you see one cup, get your eyes at ground level and you will usually see twenty.

Reading the Cup

A cup fungus gives you fewer characters than a gilled mushroom, so read each of them carefully.

Start with shape and size. Fruit bodies begin as closed, almost spherical buttons that split open and expand into shallow cups, typically half a centimetre to three centimetres across. With age they flatten out, and the margin becomes wavy, split or irregularly lobed where neighbouring cups have crowded each other. There is no true stalk, though the base may narrow into a short, buried pinch of tissue.

Now separate the two surfaces. The inner surface, which is the fertile hymenium, is the violet one: lilac to purple, sometimes with a brownish or vinaceous cast in older material, and always smooth, matte and slightly moist looking. The outer surface is distinctly paler, whitish-lilac to greyish, and finely mealy or scurfy under a lens rather than smooth. That contrast between a coloured inside and a pale, granular outside is a useful confirmation that you are in the genus Peziza rather than looking at a gelatinous fungus.

Flesh, Texture and Handling

Lift a cup with a knife blade rather than fingers; they tear easily. The flesh is very thin, often under a millimetre, brittle and watery, and it snaps rather than stretches. There is no gel layer and no rubberiness. If a specimen squashes into a jelly-like smear, you are not holding a Peziza.

There is no colour change on cutting or bruising worth recording, and no latex. Old cups simply darken to a dull purple-brown and eventually collapse into the soil. Because they are so thin, dried material shrivels to a small dark flake that is almost unrecognisable, so photograph and note the fresh colours in the field.

The Spore-Bearing Surface and How It Behaves

The fertile surface of a cup fungus is not made of gills, pores or teeth but of a smooth layer of spore-shooting cells. You can prove this in the field. Hold a mature cup up to the light, breathe warm damp air onto the hymenium or gently squeeze the margin, and after a few seconds a faint white puff of spores lifts off the surface like smoke. Not every specimen will oblige, but when it happens it is a satisfying confirmation of an ascomycete rather than a gilled fungus.

Taking and Reading a Print

Because the spores are actively fired upwards, a conventional downward print does not work. Instead, invert the cup over a glass slide or a piece of dark card, resting it on two matchsticks so the hymenium faces down, and leave it in a covered container for an hour or two. The deposit is white to very pale cream and thin.

Microscopy is where this species is genuinely settled. Spores are ellipsoid, roughly twelve to sixteen by seven to nine micrometres, colourless, and importantly smooth or very nearly so, without obvious warts, spines or a coarse network, and generally without prominent oil droplets. The paraphyses are swollen at the tip and carry the purple pigment that gives the cup its colour, and the tips of the asci turn blue in iodine solution. Anyone working seriously on burnt-ground cups will need a microscope, because several close relatives are separated on spore ornamentation alone.

Substrate and Season

The substrate is burnt soil, charcoal, and ash-enriched mineral ground, occasionally the charred surface of half-burned wood lying on that ground. Violet Fairy Cup is one of the pioneer fungi that colonise a fire site once the heat has gone, typically appearing in the first one to three seasons after the burn, most abundantly in spring and early summer and sometimes again in autumn after rain. Once vegetation closes over the burnt patch, the fungus disappears from that spot.

Separating It from the Look-Alikes

Peziza praetervisa grows in exactly the same burnt places, at the same season, and looks extremely similar in the field. It tends to be a more strongly violet or lilac cup, and its spores are finely warted rather than smooth. Without a microscope, most field records of purple burnt-ground cups are best left at the level of the group.

Peziza echinospora and its allies also occupy fire sites, but are typically browner or more olive-tinged inside, with coarsely spiny spores.

Charcoal Cup, Geopyxis carbonaria, shares the habitat but is a completely different colour: pale orange-brown to tan, with a distinctly toothed or scalloped whitish margin and a short but real stalk.

Anthracobia species are much smaller, bright orange, and often carry dark brown hairs around the margin visible under a lens.

Pyronema omphalodes forms pinkish-orange, cushion-like crusts rather than open cups, often fusing into a continuous felt.

Purple Jellydisc, Ascocoryne sarcoides, is superficially the right colour but grows on dead hardwood, not soil, and is rubbery and gelatinous rather than thin and brittle.

A Field Checklist

Burnt, charcoal-flecked ground; scattered colonies of small cups; violet to lilac inner surface with a paler, mealy outer surface; very thin brittle flesh; no stalk; spores puffed upwards rather than dropped; smooth ellipsoid spores under the scope. That combination places a find at Violet Fairy Cup within the burnt-ground Peziza group.