Dappled Webcap Identification Guide

The First Impression

Autumn, broadleaf woodland on acid to neutral ground, often on a mossy bank or beside a well-worn path under beech or birch. A medium-sized mushroom is pushing through the leaf litter, and the striking thing is the pattern on its cap: a pale ochre to whitish ground flicked and blotched with flat brick-red to coppery scales, as if paint had been shaken over it. Nothing else of that size in autumn woodland is patterned quite that way.

Take the whole fruitbody out of the litter, including the base of the stem, and take a young one as well if there are several. Both the veil and the colour change described below are best read on immature material.

Reading the Cap

The cap is 3 to 8 cm across, hemispherical at first, then convex and finally flat or shallowly wavy. The surface is dry, never gluey. Its ground colour is whitish to pale ochre-cream, and over that lie appressed fibrillose scales and patches of copper-red to brick-red, densest at the centre, where they may run together into an almost continuous rusty disc, and progressively sparser towards the margin, so the pale ground shows through between them. That gradient is the dappling the name refers to.

The margin is inrolled when young and often carries fine pale veil fibres. With age the red scales darken and the whole cap can look duller and more uniformly rust-brown, so young caps show the character best.

Reading the Gills and the Veil

The gills are adnate to notched, moderately crowded and fairly broad. Colour progresses through the season of a single fruitbody: whitish-cream or pale clay when young, then ochre to cinnamon, and finally a saturated rust-brown when the spores mature. The edge is paler and may flush reddish with handling or age.

Before you look at anything else, check a young, unopened cap for the cortina. This is a fine cobwebby veil spanning the cap margin to the stipe, best seen by holding the specimen against a dark background or backlighting it. It is delicate and vanishes early. In older specimens all that remains is a fibrillose zone on the upper stipe, often stained rust-brown where falling spores have collected on it. Finding either the cortina or its rust-stained remnant is what puts the specimen in the webcap group and rules out mushrooms with true membranous rings.

Reading the Stipe and Base

The stipe is 4 to 9 cm tall and 0.8 to 1.5 cm thick, cylindrical, often tapering slightly downwards or a little swollen at the base. It starts whitish, but is quickly overlaid from the base upwards with the same brick-red to orange-red fibrils, frequently arranged in incomplete bands or girdles, while the apex tends to remain pale. Having the same red scaling on both cap and stipe is a useful consistency check.

The base sits in soil and litter with white mycelial threads binding debris. There is no volva, no bulb with a rim, and no ring.

Flesh and Colour Change

This is the confirming test. Split a fresh fruitbody in half lengthways with a sharp blade and lay the halves cut face upwards. The flesh is white to cream at first. Within a few minutes yellow develops, most obviously in the stipe base and lower stipe, deepening to saffron or orange and often taking on reddish tones after longer exposure. Scratching the stipe surface produces the same yellowing followed by a reddish response.

Do the test on genuinely fresh material and give it time; old, waterlogged or frost-damaged specimens react weakly or not at all.

Taking a Spore Print

Set a mature cap gills-down on white paper, cover it and leave it four to eight hours. The print is rust-brown to ochre-brown, and it must be taken on white, because a rusty deposit on dark card looks indistinguishable from a pale one. That colour is a genus-level clincher: it excludes the white-spored gilled mushrooms outright and separates the specimen from the dark purple-brown and black-spored groups.

Under the microscope the spores are subglobose to broadly ellipsoid, about 6 to 7.5 by 5 to 6 micrometres, and distinctly warted.

Substrate, Season and Ecology

The species is ectomycorrhizal, forming root partnerships with broadleaf trees, above all beech and birch, with oak also frequent. It prefers acid to neutral soils and appears on banks, mossy slopes, path edges and in clearings where the litter is thin.

It grows from soil, not from wood, so if the base seems to be attached to a log, dig it out and check; almost invariably the stipe is rooted in mineral soil beneath.

Fruiting runs from late summer through autumn, usually as scattered single fruitbodies or small groups of two or three rather than large troops.

Separating the Look-alikes on Morphology

Cortinarius rubicundulus is the nearest relative in appearance. Its ground colour is more distinctly pale yellow to straw and the scales are a duller reddish-brown, so the contrast is softer; more usefully, it stains a strong, bright yellow all over on handling rather than developing yellow chiefly in the cut base, and it favours richer, often calcareous soils.

Cortinarius pholideus has a scaly cap too, but the scales are dark brown, the stipe carries shaggy dark girdles, and there are violet tints at the stipe apex and in the young gills. It is a birch associate.

Cortinarius bulliardii shows red only as a distinct patch or zone at the base of the stipe, with an unscaly cap.

Scaly Pholiota species also have a rust-brown spore print, but they grow in clusters on wood, usually have a viscid or gluey cap surface, and possess a true ring rather than a cobwebby cortina.

Scaly Tricholoma and Lepiota species can look superficially similar but give a white spore print and have no cortina.

Cystoderma amianthinum is much smaller, granular rather than scaly, and white-spored.

Inocybe species have rust to snuff-brown spores but radially fibrillose or split caps without discrete red scales.

Working Checklist

• Dry, pale cream to ochre cap flecked with flat brick-red to coppery scales, densest at the centre
• Cortina in young specimens; rust-stained fibrillose zone on the upper stipe later
• Gills pale clay ageing to rust-brown, adnate to notched
• Whitish stipe overlaid with red fibrils in bands, from the base upwards
• Cut flesh yellowing in minutes, strongest in the stipe base, later reddening
• Rust-brown spore print taken on white paper
• Ectomycorrhizal with beech, birch and oak on acid to neutral soil, in autumn