Gypsy Mushroom Identification Guide

The First Impression

The Gypsy Mushroom looks, oddly, like a well-fed field mushroom that has been dusted with hoar frost. You find it in northern or upland conifer forest, on acid ground carpeted with bilberry, cowberry, heather and thick moss, usually under spruce, pine or birch. It grows in scattered troops, sometimes many across a slope, and the caps push up through the dwarf shrub layer as pale ochre eggs. Two things register immediately: the cap has a silvery, frosted bloom that looks like a fine bloom on a plum, and the stem carries a proper white skirt, which is not what you expect on a Cortinarius. Once the cap flattens, the third character appears, a set of radiating wrinkles and creases toward the rim that give the species its name, caperatus, meaning wrinkled.

Working Through the Cap

Caps run 5 to 12 cm across, occasionally to 15 cm. They begin as tall ovoid eggs, almost acorn-shaped, then open through convex to broadly flattened with a low umbo. The ground colour is straw, clay-buff, ochre or pale tan, sometimes with a faint lilac cast when very young, deepening slightly with age.

The surface is where the work is. Young caps are coated over the centre with a silvery-white, silky, frost-like film left by the universal veil; it can look almost like a dusting of flour or a fine hoar. This bloom wears off from the disc outward, so mature caps often show it only as a pale patch on top or as fibrillose scraps near the rim. As the cap expands the flesh cannot keep up, and the outer half develops distinct radial wrinkles, furrows and creases, so the rim looks crumpled, sometimes slightly wavy or splitting. The surface is dry and silky, never sticky or slimy.

The Gills

Underneath, the gills are the key to the genus. They are adnate to adnexed, moderately crowded, and their colour changes decisively with age. Young gills are pale clay, whitish-buff or faintly greyish; mature gills are ochre then rust-brown to cinnamon as the spores ripen. Look along the gill edge with a lens: it is uneven, minutely eroded or serrated, and often paler than the face, another useful confirmation. Rust-coloured dust settles on the ring and upper stem of older specimens, which you can see with the naked eye.

The Stipe and the Ring

The stem is stout, 5 to 12 cm tall and 1 to 2.5 cm thick, roughly equal in width or thickening slightly downward, solid and firm, whitish to pale buff and finely fibrillose. Its defining feature is a persistent, membranous, upstanding ring, white to cream, positioned around the middle or slightly above. Most webcaps have only a cobwebby cortina that disappears into a rusty fibrous zone; this species has a genuine ring you can lift with a fingernail, which is why it spent decades in its own genus, Rozites.

Do not stop at the ring. Look at the very base. In fresh specimens there is often a thin, fugitive, whitish band or sheath of universal veil tissue clasping the base, a faint volva-like girdle. It is delicate and frequently rubbed away, but when present it is a strong supporting character. Dig the base out rather than snapping the stem so you can see it, along with white mycelial cords binding the moss and needle litter.

Flesh, Cut Surface and Odour

Slice the fruitbody vertically. The flesh is white to very pale buff, thick and firm in the cap, fibrous in the stem, and it does not change colour on exposure; there is no blueing, reddening or yellowing. In old specimens the stem may become soft or hollowed by larvae. The smell is mild and pleasantly fungal, sometimes faintly earthy or of damp cellar, with nothing pungent, mealy or sharp about it.

Taking a Spore Print

Cut the cap free and set it gills-down on white paper under a bowl for three to six hours. The deposit is rusty brown, sometimes described as ochre-brown or snuff-coloured, and it is unmistakable against white paper. That rusty print is the anchor of the identification: any mushroom with a membranous ring and a rusty print belongs to a small set of possibilities. Under a microscope the spores are almond-shaped or lemon-shaped and coarsely warted, typical of Cortinarius.

Habitat, Partners and Season

This is an ectomycorrhizal species with a distinctly northern and montane distribution. It partners with conifers, chiefly Norway spruce and Scots pine, and with birch, and it favours poor, acid, sandy or peaty soils under a dwarf-shrub understorey. Bilberry heath under spruce is the classic setting; upland pinewood, boreal forest and mossy conifer plantations all produce it. It fruits from mid or late summer into autumn, roughly late July to October, and it often appears in large scattered arcs across a hillside after a wet spell. It grows from soil and moss, never on wood.

Separating It from Look-alikes

Other Cortinarius species share the rusty spore print and the general build, but almost all of them have a cortina rather than a membranous ring; on a mature specimen you see only a belt of rusty fibrils on the stem, not a lifted skirt. Any webcap with a true ring in this habitat, a wrinkled ochre cap and a frosted bloom is very likely this species. Species such as Cortinarius armillatus have red-brown girdles around the stem base rather than a ring; Cortinarius traganus is lilac all over with a saffron interior.

Agaricus species also have a membranous ring, but their gills go pink then chocolate-brown and their spore print is dark chocolate, not rust. Their gills are free rather than attached, and their caps lack the frosted bloom and radial wrinkling.

Pholiota species can be ochre with a ring, but they are wood-dwelling, usually clustered on stumps and trunks, and typically have scaly or slimy caps.

Phaeolepiota aurea superficially resembles a large ringed ochre mushroom but is granular-powdery all over, brighter golden-orange, and grows in rich nitrogen-loaded ground near nettles and roadsides rather than in acid bilberry heath.

Stropharia and Psathyrella species with rings give purple-black or dark brown-black prints, ruling them out at once.

Finally, Amanita species have white spore prints and free gills, and their ring is accompanied by a bulb or sac; the rusty gills of a mature Gypsy Mushroom exclude them instantly.

Field Checklist

Ochre to clay cap with a silvery frosted bloom when young and radial wrinkles at the rim; attached gills turning rust-cinnamon; stout pale stem with a genuine membranous ring; often a faint whitish band at the stem base; white unchanging flesh; rusty-brown spore print; on acid soil and moss under spruce, pine and birch in northern and upland forest.