The Wonderful World of Russulas

Scarlet, violet, primrose, olive, wine-red and green. Walk through a British woodland in late summer and Russulas lie scattered across the floor like fallen jewels. They’re among our most beautiful fungi and, without doubt, among the most frustrating to identify. Let’s explore why, and how you can start to crack them.

There are more than 150 species of Russula in Britain. We call them brittlegills, and they appear from midsummer until the first hard frosts, often in astonishing numbers, and almost any woodland walk will turn up a few.

But here’s where it gets complicated. That glorious palette of colours, the very thing that makes Russulas so eye-catching, is also one of the least reliable ways to tell them apart. A single species can wear several colours, and several species can look almost identical. Russulas reward patience, curiosity and a willingness to use every one of your senses.

Jewels of the Woodland Floor

Every Russula lives in partnership with trees. Its mycelium wraps around the fine tips of tree roots, trading water and minerals from the soil for sugars the tree makes from sunlight. Because of this mycorrhizal partnership, each species tends to grow with particular trees: some with beech, some with birch, others with oak, pine or spruce. Find the tree, and you’ve already narrowed the field.

Look closely at a Russula and you’ll see a fungus that seems carved rather than grown. The caps are often smooth and polished, sticky after rain. The gills are neat and orderly. The stems are usually pale, stout and clean, with no ring and no cup at the base. There’s a solidity to them that feels almost architectural, right up until you try to bend one.

The snap test

Here’s the party trick. Bend a Russula stem and it snaps cleanly, like a stick of chalk. Run a fingertip across the gills and they crumble. That brittleness comes from clusters of rounded cells called sphaerocysts in the flesh, and it gives the whole group its common name.

Their close relatives, the milkcaps, share that crumbly texture. The difference? Break a milkcap and it will usually ooze droplets of milk. A Russula stays dry.

Why Russulas Are So Tricky

If Russulas are so easy to recognise as a group, why are they so hard to name to species? Partly it’s the sheer number of them. Partly it’s that the features separating them are subtle: a slightly different shade of spore print, a hint of heat on the tongue, a faint smell of fish. And partly it’s that colour, our most natural starting point, is so unreliable. Rain washes the colour from a cap, age fades it, and some species come in a whole spectrum of shades.

The Charcoal Burner, Russula cyanoxantha, is a perfect example. Its cap can be violet, purple, slate-grey, blue-green or entirely green, often all within the same patch of woodland. Identifying Russulas means learning to look past the obvious and gather a whole set of clues together.

The Russula Toolkit: Key Identification Features

Experienced Russula hunters work through a set of features, each one narrowing the possibilities. Here are the most important.

1. Spore print colour

This is the single most useful character. Russula spore prints range from pure white through cream and pale yellow to deep ochre. Take a print on white paper (our guide to better observations explains how) and compare it against a colour chart in good daylight. The differences can be subtle, so a thick deposit is best.

You can get an early hint from the gills. Mature gills that stay white or very pale suggest a pale print. Gills that turn cream, yellow or ochre as the cap opens suggest a darker one.

2. Taste

Taste is one of the strangest but most useful Russula characters. Some species are completely mild. Others are so fiercely hot that the burn builds on your tongue for a minute or more. The Sickener, Russula emetica, and the Beechwood Sickener, Russula nobilis, are both famously fiery.

3. Gills

Gently run a finger across the gills. In most Russulas they crumble. In the Charcoal Burner they’re flexible and feel slightly greasy, a feature that identifies it on the spot. Look too at how crowded or widely spaced the gills are, whether they fork, and how they join the stem.

4. Cap skin

Try peeling the cap skin from the edge towards the centre. In some species it peels almost all the way, in others hardly at all. Note whether the cap is shiny, matt, sticky or velvety, and whether the margin is grooved.

5. Colour changes

Scratch or cut the stem and wait a few minutes. Many Russulas stay white. Others turn grey, red or brown, and the Blackening Brittlegill, Russula nigricans, goes red and then slowly black. Some species turn yellow where they’re handled.

6. Smell

Sniff the gills, then a freshly broken piece of flesh. The Crab Brittlegill, Russula xerampelina, and its relatives smell of shellfish, especially as they age. Others smell fruity, honeyed or even of geraniums. The Geranium Brittlegill, Russula fellea, is named for its scent.

7. Chemical tests

Serious Russula enthusiasts carry a small kit of chemical reagents. A drop of iron sulphate (FeSO₄) turns the stem of the crab-scented species green. Tincture of guaiac gives a blue-green reaction whose speed and strength vary between species. These tests aren’t essential when you’re starting out, but they’re a fascinating next step.

8. The trees

Always note the nearby trees. The Birch Brittlegill, Russula betularum, grows with birch. The Beechwood Sickener grows with beech. The Bloody Brittlegill, Russula sanguinaria, grows with pine. Knowing the host can cut a long list of possibilities down to a handful.

A Few Russulas to Get to Know

Every Russula hunter has their favourites. Here are four to look out for, all recorded on Field Mycologist.

The Book Every Russula Hunter Needs

If you want to take your Russula identification seriously, there’s now one essential companion. The Genus Russula in Great Britain by Claudi V. Soler, Felix Hampe, Geoffrey Kibby and Mario Tortelli, published in August 2026, is the most comprehensive study of the genus in Britain to date.

It covers more than 150 British species, plus 20 from further afield, with colour photographs, colour illustrations and micrographs of spores and hyphae for each one. There are both diagnostic and synoptic keys, and a spore colour chart on a separate card that you can take into the field. It’s also the first book in English in which the DNA of almost every species described has been sequenced, the product of some 30 years of research. It’s available from Summerfield Books.

Embrace the Puzzle

Here’s the honest truth, you won’t identify every Russula you find. Nobody does. Even the experts send specimens for microscopy or DNA sequencing. But every Russula you examine carefully, with a spore print, a sniff, a note of the nearest tree and perhaps a cautious taste, teaches you something new.

And your records matter. Russulas are vital partners of our woodland trees, and knowing where each species grows helps us understand the health of our woods. So next time you spot a flash of scarlet or violet among the leaves, crouch down, gather your clues and record it on Field Mycologist. Even a record to genus level adds to the picture, and your fellow recorders and Identifiers will be ready to help you take it further.