Gypsy Mushroom

Cortinarius caperatus is the odd one out among the webcaps. Where almost every other member of the genus leaves only a cobwebby fibrous zone on the stem, this species produces a genuine membranous ring, which is why it was for a long time placed in its own genus as Rozites caperata. Molecular work eventually returned it to Cortinarius, but its distinctive veil structure still makes it stand apart in the field.

The cap is equally characteristic. It is a warm ochre or clay-buff, coarsely wrinkled and radially furrowed like crumpled paper, and it is overlaid, especially towards the centre, with a fine silvery-white bloom of veil fibres that looks like a light frost or a dusting of icing sugar. The epithet caperatus means wrinkled and refers directly to that surface.

It is a common and often abundant fungus in the boreal and montane forests of the northern hemisphere, fruiting in numbers among bilberry and moss in acidic conifer woodland, and it is one of the more easily identified members of a genus that is otherwise a byword for taxonomic difficulty.

Cap

The cap is 5-12 cm across, egg-shaped or almost spherical when young and expanding to convex and finally broadly flattened with a low broad umbo. The colour is ochre, clay-buff, tan, or pale straw brown, sometimes with a faint lilac cast when very young. The surface is dry and characteristically wrinkled, with radial furrows and puckering most obvious towards the margin, and it carries a silvery-white to lilac-white frosted bloom of fine veil fibres over the centre which weathers away with age and rain.

Gills

The gills are adnate to emarginate, moderately crowded, and pale clay or greyish buff at first, ageing through ochre to a dull rusty cinnamon brown. The gill edges are often minutely white-fringed and slightly ragged or crenulate, another useful supporting character.

Stipe

The stipe is 5-12 cm long and 1-2.5 cm thick, whitish to pale ochre, firm and solid, more or less equal or slightly swollen at the base. Above the middle it carries a persistent white membranous ring, upturned and skirt-like, often stained rust by falling spores. Lower down there is frequently a second, faint whitish band or girdle left by a lower veil, and the base may be slightly bulbous but never sits in a sac.

Flesh and spore print

The flesh is thick, firm, and whitish to pale buff, unchanging or barely changing when cut, with a mild fungal odour. The spore print is rusty ochre-brown, confirming its place in Cortinarius despite the untypical ring.

Gypsy Mushroom is a species of acidic, often nutrient-poor forest soils. It is most abundant in coniferous woodland with Norway spruce and Scots pine, and also occurs in mixed and birch woodland, upland heath edges, and montane forest. It is strongly associated with a ground layer of bilberry, cowberry, heather, and mosses, and it often fruits in large numbers in the same patches year after year.

The season is late summer through autumn, peaking after sustained rain. The distribution is circumboreal, covering northern and montane Europe including Scandinavia and Scotland, northern Asia, and northern North America, and it is generally one of the commonest large webcaps within that range.

Cortinarius caperatus is ectomycorrhizal, forming sheathing partnerships with the fine roots of conifers and birch. The mycelium encases feeder rootlets and grows between their outer cells, creating the Hartig net through which mineral nutrients and water move into the tree and photosynthetic sugars move into the fungus. On the thin, acidic, often waterlogged soils it prefers, this relationship is a major route by which trees obtain nitrogen and phosphorus.

As an obligate symbiont it cannot be grown apart from a host, and its abundance in mature spruce and pine forest reflects the extent of the root systems it draws on. Its mycelial network is part of the dense below-ground fabric of boreal forest soil, holding structure and connecting roots, and its rusty spores are released in autumn to be carried by air currents and by the invertebrates and small mammals that feed on the fruiting bodies.

Other large webcaps such as members of the Cortinarius triumphans and C. varius groups share the rusty spore print, but all of them leave only a cobwebby fibrous zone on the stem instead of a true membranous ring, and none has the combination of a wrinkled cap and a silvery frosted bloom. The Golden Bootleg, Phaeolepiota aurea, has a similar tawny colour and a large ring, but its cap and stem are coated in a granular, powdery golden layer rather than a silky bloom, and its overall colour is a far brighter orange-gold.

Agaricus species also carry a membranous ring but have gills that are completely free of the stem, pass through a clear pink stage, and finish dark chocolate to blackish brown, with a matching dark brown spore print rather than a rusty one. Amanita species have a white spore print, white gills, and a bulb or sac at the stem base. Pholiota species have rusty prints too but are typically scaly and viscid-capped and fruit in clusters on wood rather than singly from forest soil.