Bloodred Webcap | Cortinarius sanguineus Identification Guide

The Picture at First Sight

You are in conifer forest, most likely spruce, on acid ground with a deep carpet of feather moss, bilberry and needle litter. Among the green, a small patch of intense colour catches the eye at ankle height: a few caps of a deep, saturated blood-red or dark crimson, each no bigger than a large coin, standing on stems of the same colour. The impression is of one colour running through the entire fungus, top to bottom, which is unusual and immediately narrows the field. They usually appear in scattered groups of three to a dozen rather than in tufts, and often half-hidden in moss, so it pays to part the moss around any red cap you see and check whether the stem is red too.

Reading the Cap

Cap diameter is typically 2 to 5 cm. Young caps are neatly convex, sometimes almost conical, and they expand to flat or slightly upturned with a low central bump that persists in most collections. The surface is dry, never slimy or greasy, and under a lens it is finely fibrillose or silky, with radiating hair-like fibres that catch the light. Colour is a deep blood-red to dark purplish-red or brick-crimson, more or less even across the cap, sometimes a little darker at the centre and paler at the edge in older material or after strong sun. The margin is thin and stays inturned for a long time in young specimens, and old caps can develop dark blackish-red patches where they have weathered.

The Gills

This is where the identification really turns. The gills are the same deep blood-red as the cap when young, adnate to narrowly attached, moderately crowded, and fairly narrow. As the spores mature the red picks up a rusty, cinnamon or ochre-brown overlay, so an old specimen looks dirty rust-red with the original colour showing where the gills are protected near the stem. Look for that shift, because the developing rust tone is the first honest clue to the spore colour of the group. Gill edges are even and concolorous, and there is no dark marginal line.

The Stem, the Veil and the Base

The stem is 3 to 7 cm long, 3 to 8 mm thick, more or less equal or slightly swollen below, and coloured like the cap: red, sometimes with a yellowish or ochre tinge at the very base. Its surface is finely fibrillose and often carries the remains of a cobwebby veil.

That veil, the cortina, is the character that defines the whole genus, and it needs to be checked deliberately. In a button or a very young cap you should be able to see fine silky threads stretching from the cap margin to the stem, like the ghost of a spider's web. As the cap opens these threads collapse onto the stem, and as spores are shed they catch in the residue and dye it rusty brown, leaving a faint rusty girdle or a scatter of rusty fibrils partway up the stem. A single fresh button in the collection is worth ten mature caps for this purpose, so always dig for one. At the base, look for reddish to pinkish mycelial threads binding moss and needles.

Flesh and Colour Change

Slice a fruit body from cap centre to stem base. The flesh is thin, firm and coloured, ranging from reddish to reddish-buff, paler than the surface but never pure white. Nothing dramatic happens on cutting: no rapid blueing, no milk, no strong bruising reaction. The consistency is fibrous in the stem rather than brittle, and the stem does not snap cleanly like a chalk stick. That fibrous texture, together with the coloured flesh, helps rule out the brittle red-capped groups.

Taking and Reading a Spore Print

This single test resolves nearly every problem with red mushrooms. Cut the cap free, place it gills-down on white paper or a glass slide, cover it with a cup and leave it for four to eight hours. The print is a distinct rust-brown to cinnamon-brown. That result places the collection with the webcaps and excludes the whole array of red-capped fungi with white or cream prints. Microscopically the spores are small, ellipsoid to almond-shaped, roughly 6 to 9 micrometres long, and finely warted, and the tissues carry the yellow to red anthraquinone pigments typical of the red and orange-gilled webcap group.

Substrate, Season and Ecology

This is a mycorrhizal partner, not a decomposer, so it never grows on wood and never on dung. It fruits from soil in coniferous forest, above all with Norway spruce, and more rarely with pine, on acid, often nutrient-poor and mossy ground. Damp, mossy hollows, bilberry-rich slopes and old, undisturbed forest are the productive spots, and upland and northern forests are generally better than lowland plantations. Season is late summer to late autumn, with the main flush after the first prolonged wet spell of the season. Because the fungus is tied to the tree roots, finding it means there is a mature spruce within a few metres, which is itself a check on the identification.

Separating the Red-Gilled Webcaps and Other Red Mushrooms

• Surprise Webcap, Cortinarius semisanguineus, has the same blood-red gills but an entirely different cap: ochre, tawny, olive-brown or yellow-brown, never red. If cap and gills disagree in colour, you have this species rather than the fully red one. The stem is also yellowish rather than red.
• Cortinarius puniceus is a similar deep red species but is associated with broadleaf trees, particularly oak and beech, and is usually a little larger and more purple-toned.
• Cortinarius cinnabarinus is a brighter cinnabar to brick-orange red, grows with beech and other broadleaf trees on richer soils, and lacks the dark blood tone.
• Orange-gilled relatives such as Cortinarius croceus have olive-brown to yellow-brown caps with saffron to orange-yellow gills rather than true red.
• Red Russula species such as the brittlegills have white to cream gills, a white stem, brittle flesh that snaps like chalk, no cobwebby veil, and a white to cream spore print.
• Red waxcaps have thick, waxy, widely spaced gills, a white spore print, and grow in unimproved grassland rather than conifer forest.
• Small red bonnets are far more slender and delicate, grow on wood or litter, and have white spore prints.

Field Checklist

Conifer forest with spruce; a small, dry, silky, wholly blood-red fungus; red gills turning rusty with age; a cobwebby veil leaving rusty fibrils on a red stem; coloured flesh; and a rust-brown spore print. Every one of those must agree before the name is applied.