The Sickener

The Sickener is the type species of Russula, the genus of brittlegills, and its scientific name Russula emetica has been in use since the eighteenth century. Like all brittlegills it has no ring and no volva, its stem breaks with a clean chalky snap, and its flesh has the granular texture that comes from spherical cells packed among the hyphae.

It is one of the most striking red mushrooms of northern woodland, with a cap of an intense, almost translucent scarlet to cherry red that contrasts sharply with the pure white gills and stem. The cap surface is smooth and shiny when moist, and the coloured skin can be peeled back almost to the centre, a character used routinely to separate it from other red brittlegills whose cuticles peel only a short distance.

Red brittlegills are notoriously difficult as a group, and R. emetica in the strict sense is now understood to be one of several closely related taxa distinguished by habitat and by fine details of cap peeling, stem tint and spore ornamentation. In current usage the true Sickener is the conifer and sphagnum species, with birch and beech woodland hosting its own near-identical counterparts.

Cap

3-10 cm across, convex then flattening and often becoming shallowly depressed, sometimes with a low central dimple. The surface is smooth, shiny and viscid when moist, drying matt. Colour is brilliant scarlet to cherry or blood red, sometimes fading to pinkish or developing washed-out cream patches after rain. The margin becomes distinctly grooved or furrowed with age. The red skin peels easily and cleanly, typically two-thirds to nearly all of the way to the centre, revealing white flesh beneath.

Gills

Adnexed to nearly free, fairly well spaced, broad, and pure white to very faintly cream, keeping their whiteness into maturity. They are brittle and shatter readily when stroked, the normal condition for the genus. Gill edges are even and concolorous.

Stipe

4-9 cm tall, 0.7-2 cm thick, cylindrical or slightly clubbed toward the base, pure white or with a faint cream flush in age, and often finely longitudinally wrinkled. It is fragile, becoming hollow or chambered, and snaps cleanly across. There is no ring and no volva.

Flesh and spore print

The flesh is white, thin, and brittle, sometimes flushed red directly under the cap cuticle, and it does not change colour when cut. The spore print is white to the faintest cream. Spores are broadly ellipsoid with prominent warts joined into a partial network.

Russula emetica in the narrow sense is a fungus of wet, acidic, conifer-dominated ground. Typical sites are spruce and pine forest with a deep moss carpet, boggy woodland margins, sphagnum lawns, wet heath with scattered pines, and peaty hollows. It is much less common on dry mineral soils and is largely absent from calcareous ground.

Fruiting runs from midsummer to late autumn, peaking in August and September in northern Europe. Fruit bodies grow singly or scattered, often half buried in moss with only the scarlet cap showing. The species is widespread across northern and montane Europe, boreal Asia and northern North America, with related red brittlegills replacing it in warmer or broadleaved habitats further south.

This is an ectomycorrhizal species that forms root sheaths on conifers, principally spruce and pine. The fungal mantle around the fine roots and the Hartig net between the root cells create a large exchange surface through which the tree receives water and mineral nutrients, particularly phosphorus and nitrogen bound in the acid peat, and the fungus receives photosynthetic sugars.

In nutrient-poor, waterlogged, acidic soils this partnership is especially important, because much of the available nitrogen is locked into slowly decomposing organic matter that tree roots cannot access alone. Brittlegills also produce large numbers of spores that are dispersed by air currents and by animal traffic, and the soft fruit bodies are frequently grazed by slugs and mined by fungus gnat larvae, which in turn carry spores through the forest.

The red brittlegills form a difficult complex. Russula betularum is paler, a washed pink rather than scarlet, more slender and thin-fleshed, and grows with birch in damp ground. Russula mairei (also treated as R. nobilis) grows under beech, is smaller and firmer with a cuticle that peels only about halfway and gills with a faint greenish or bluish tint. Russula sanguinea is distinguished at once by its cuticle, which barely peels at all, and by a stem flushed pink or rose rather than pure white.

Russula rosea (formerly R. lepida) has a dry, matt, almost chalky-bloomed red cap and firm hard flesh, quite unlike the shiny viscid cap and fragile flesh of the Sickener. Away from the genus, the red-capped Amanita muscaria is separated instantly by its white warts, a skirt-like ring on the stem and a rimmed bulbous base, none of which occur in any brittlegill.