Deadly Webcap Identification Guide

The Ground You Are Standing On

The Deadly Webcap belongs to cool, wet conifer forest. The typical setting is upland or northern spruce and pine woodland with a deep, springy floor of Sphagnum and feather mosses, bilberry and crowberry, boggy hollows and standing water not far away. In the far north the same fungus follows birch and dwarf willow into damp montane scrub. It is a mushroom you find with wet knees.

The first impression is of a strikingly foxy, tawny-orange cap sitting high on a slim, pale-banded stem, often pushing through moss so that only the pointed top shows. The colour is warm and dry-looking, more brick or cinnamon than yellow, and the shape has a distinctly sharp peak. Once the general Cortinarius character registers, that combination of pointed umbo, dry felted cap and yellow-girdled stem in wet conifer moss is what to work with.

Reading the Cap

Caps are 3 to 8 cm across. Young fruitbodies are conical to bell-shaped with the margin pressed close to the stem; expanded ones become broadly conical or convex but almost always keep a pronounced, sharply pointed umbo at the centre. That acute papilla is one of the most useful shape characters in the group.

The surface is dry, never viscid or slimy, and finely felted, fibrillose or minutely scaly, so that it catches the light with a matt, suede-like texture. In older caps the fibrils can lift into small appressed scales, strongest at the centre. Colour runs from tawny orange through foxy red-brown to a rich brick, generally darker at the umbo and slightly paler at the rim. The cap is not markedly hygrophanous, so colour is fairly stable regardless of weather, which is a helpful contrast with Galerina and Kuehneromyces.

The Gills

Turn one over. The gills are thick, broad, and notably distant, with clear spaces between them and few short intermediate gills. They are adnate to slightly emarginate at the stem. Colour begins ochre-yellow to pale cinnamon, then deepens through cinnamon to a saturated rusty brown as the spores ripen, often ending close to the colour of dried orange peel. Wide, thick, well-spaced rusty gills are far more Cortinarius than Galerina, whose gills are noticeably more crowded and thinner.

The Cortina and the Stipe

Look at the young fruitbody for the cortina, the cobwebby partial veil that runs from the cap margin to the stem in place of a membranous ring. In this species the cortina is yellowish and delicate; it collapses onto the stem rather than forming a collar, and in mature specimens it survives only as a rusty-dusted fibrillose zone.

The stipe is 5 to 11 cm tall and 5 to 15 mm thick, usually tapering downward to a narrower base and often somewhat rooting in the moss. Its ground colour matches or slightly pales the cap. The defining feature is the veil banding: irregular, transverse girdles of ochre-yellow to lemon-yellow fibrils spaced along the lower two-thirds of the stem. Those yellow bands on a tawny stem are the strongest single field character. Peel back the moss to see them, because the lowest ones are often buried.

Flesh, Colour Change and Odour

Split a fruitbody lengthwise. The flesh is firm and pale ochre to yellowish in the cap, becoming more saffron or tawny down the stem, and it may be slightly darker where the yellow veil bands attach. There is no blueing, no reddening and no rapid darkening on exposure, though the cut surface dulls slowly as it dries. The smell is faint and slightly raphanoid, a mild radish note, and never strongly sweet or aromatic.

Taking a Spore Print

Set a mature cap gills-down on white paper under a cover for four to eight hours. The deposit is a strong rust-brown, and in the field you can often anticipate it from the rusty dusting already lying on the cortina zone and on the caps of lower fruitbodies in a group.

Microscopically the spores are large for the genus at roughly 8.5 to 11.5 by 6.5 to 8.5 micrometres, broadly ellipsoid to almost egg-shaped, and conspicuously coarsely warted. Spore size is genuinely diagnostic here, since several similar tawny webcaps have visibly smaller or narrower spores.

Substrate and Season

Cortinarius rubellus is mycorrhizal, forming root partnerships with conifers, principally Norway spruce and Scots pine, and with birch at higher latitudes. It does not grow on wood or on rich garden soil; it needs the acid, damp, moss-dominated floor of established conifer forest or boreal woodland. Sphagnum bogs at the edge of a plantation, wet hollows in old spruce forest and bilberry-carpeted upland pine woods are all classic ground.

Season is late summer to autumn, typically August to October, following the same rain-triggered flushes as other webcaps. Fruitbodies occur singly or in scattered groups, sometimes in loose lines along a wet flush, and are rarely clustered at the base.

Separating the Close Look-alikes on Morphology Alone

Cortinarius orellanus is its nearest relative. It is a broadleaf woodland species of oak and beech on warmer soils, has a broader cap with a low, blunt or barely developed umbo, and crucially lacks the ochre-yellow girdles, its stem being uniformly yellow-brown and only faintly fibrillose.

Cortinarius gentilis is much smaller and more slender, with a darker date-brown cap and yellow veil bands, and distinctly narrower spores.

Cortinarius cinnamomeus and its allies have olive-yellow to bright yellow young gills and a smoother, more brownish cap without a strongly pointed umbo.

Cortinarius semisanguineus is easy: its gills are a striking blood-red against an olive-brown cap.

Galerina marginata is far smaller, grows directly on rotted wood, has crowded gills, a true membranous ring rather than a cobwebby cortina, and a smooth hygrophanous cap.

Gymnopilus species have brighter yellow flesh, densely crowded gills and no yellow girdling.

Hygrophoropsis aurantiaca has decurrent, forking, soft orange gills and a white to cream print.

Field Checklist

Wet conifer moss underfoot; a dry, felted, foxy-tawny cap with a sharply pointed umbo; thick, distant gills ripening rust; a yellowish cobwebby cortina replaced by a rusty fibrillose zone; ochre-yellow girdles banding a downward-tapering stem; yellowish unchanging flesh with a mild radish smell; and a rust-brown print of large, coarsely warted spores.