Dappled Webcap

The Dappled Webcap is one of the most easily recognised members of its huge genus, because almost nothing else in Cortinarius combines a pale creamy-yellow ground colour with flat, coppery brick-red scales scattered across cap and stipe. The pattern is like copper leaf flaking from a pale surface, and it holds from button to maturity.

It belongs with the dry-capped webcaps that develop a scaly outer veil, and its second useful character is internal: the white flesh slowly turns yellow and then dull reddish where it is cut or handled, a colour change unusual in the genus. Bruised areas of the stipe base often redden noticeably.

The species is a broadleaf-woodland fungus of damp acid soils, common under birch and beech across temperate Europe, and it fruits in scattered groups in leaf litter and among mosses during the main autumn season.

Cap

3-8 cm across, convex then flattening, occasionally with a low umbo. The ground colour is pale cream to whitish-yellow, and it is overlaid with flattened, appressed scales of coppery to brick or blood-red, densest at the centre and separating into a dappled pattern toward the margin. The surface is dry, never viscid.

Gills

Adnate to emarginate, moderately crowded, pale clay to buff-yellow at first and darkening steadily through cinnamon to rusty brown with maturity. Edges are paler and often minutely uneven, and damaged gills may take on reddish tones.

Stipe

4-9 cm long, more or less equal or slightly swollen at the base, whitish to pale yellow and encircled by irregular reddish to coppery scaly bands or fibrils that match the cap. The base commonly flushes yellow then dull red where handled. A faint cobwebby cortina leaves a rust-dusted zone above the bands.

Flesh & spore print

Flesh is white and firm, turning slowly yellow and then dull reddish or brick where cut or bruised, most quickly in the stipe base. The spore print is rusty brown, with broadly ellipsoid to almond-shaped, warted spores.

This webcap grows with broadleaved trees, especially birch and beech, and also with oak and hazel, on damp acid soils. It favours mossy woodland floors, shaded banks and the humid margins of woodland streams and ditches, fruiting singly or in small scattered groups among leaf litter.

The season is late summer through autumn, peaking in mid autumn after sustained rain. It is widespread across Britain, Ireland and continental Europe, common in some regions and merely occasional in others, and it is recorded from comparable broadleaf woodland in parts of temperate North America.

Cortinarius bolaris is ectomycorrhizal with broadleaved trees, chiefly birch and beech. Its mycelium sheathes the tree's short roots and grows between the outer cells to build a Hartig net, forming the exchange surface where fungal-supplied nitrogen, phosphorus and water are traded for tree-derived sugars. This is especially valuable on leached acid soils where mineral nutrients are scarce.

The yellowing and reddening of injured flesh reflects the oxidation of pigment precursors when tissue is damaged and exposed to air, a widespread fungal wound response. The mycelium is perennial, spreading slowly outward through the litter layer, and colonies fruit dependably from the same ground once autumn moisture arrives.

Cortinarius rubicundulus has a pale yellowish cap that bruises and stains yellow, but it lacks the coppery-red scales and its flesh reddens little if at all. Cortinarius bulliardii has a smooth brown cap and a stipe whose base is a bright brick-red, rather than red scales scattered over cap and stipe.

Cortinarius pholideus is also scaly but its scales are dark brown on a brown ground, and its young gills are violet. Cortinarius orellanus shares the tawny colouring but is uniformly foxy brown with a finely scaly rather than dappled cap and flesh that does not change colour.