Yellow swamp brittlegill

Overview

Yellow swamp brittlegill is a wild mushroom of northern Europe that grows with birch, and sometimes aspen, in damp ground. The catalogue records it as a cooked woodland mushroom and a birch-associated mycorrhizal fungus.

Its bright yellow cap is conspicuous, but the catalogue warns that Russula includes toxic species and that cap colour is not enough to identify one. The yellowish Russula ochroleuca, a lookalike, is described as edible but acrid in one source and inedible in another.

Description and habitat

Field descriptions give a bright yellow cap, white gills and stem, and flesh that turns grey when cut or bruised. The species grows in damp ground, often in sphagnum near ponds or lakes, in summer and autumn. One British guide reports that it can occasionally appear in spring.

Food use

Field guides describe the mushroom as mild-tasting and good to eat, and one calls it a prized wild mushroom. One source says it is best cooked, and that the flesh is not something to eat raw. The catalogue records it as a cooked woodland mushroom. Russula vitellina, a smaller species with egg-yolk-yellow gills, is also described as edible and is a near relative to compare.

Identification and safety

Brittlegill identification depends on fine details, and some relatives are acrid or unpleasant. Confirm identification by spore print and several features before eating, and check regional guidance: the sources read are mostly European field guides. Do not use this page to identify or eat wild fungi.

How to recognise a brittlegill

A mushroom is a brittlegill, a Russula, only when several features line up. The cap is usually brightly coloured. The gills are brittle: they snap when you try to bend them, and the flesh breaks cleanly like chalk instead of tearing into fibres. The stem carries no ring and no cup or sack at its base, and there are no veil remnants on the cap. The gills are attached to the stem, and a spore print is white, cream or dark yellow.

Two checks separate Russula from its look-alikes. Break a gill or cut the flesh: a brittlegill gives no milky juice, while a milkcap (Lactarius or Lactifluus) weeps latex. Then look at the stem. A ring on the stem, a cup or a sack or bulb with torn remnants at its base, or flesh that tears in fibres points away from Russula and towards Amanita, a genus that includes the deadly death cap and many other poisonous species. A mushroom with a ring or a cup at the base is not a Russula, whatever colour its cap is.

Recognising the genus is much easier than naming the species. Cap colour varies widely inside one species, so experts rely on the colour of the spore print, the taste, colour changes in the flesh, how far the cap skin peels, chemical tests and the microscope. A collector who is sure of the genus but not of the species should treat the species as unidentified.

The taste test, and what it cannot tell you

Foragers have long sorted brittlegills by taste. Break off a small piece of cap flesh or gill, chew it for several seconds and spit it out without swallowing; the burn of an acrid species can take half a minute to build. Brittlegills that taste mild are the traditional edibles. Those that taste hot, peppery or acrid, and many bitter ones, are left alone because they irritate the stomach and bowel and can cause vomiting and diarrhoea.

The method works only inside the genus. Use it once the mushroom is positively a Russula, never to decide whether an unknown mushroom is safe: the deadliest mushrooms do not taste unpleasant, and a mild taste says nothing about an Amanita, a Cortinarius or any other family. Within Russula it is a screen for rejecting species, not proof of safety. Some mild species are poor eating, rare species are poorly documented, and a few brittlegills have been linked with poisoning. Cook what you eat, start with a small portion, and identify to species where you can. This record is not a field guide.