Wrinkled Cortinarius

C. caperatus has a buff to brownish-ochre cap 5–12 centimetres (2–4+3⁄4 in) diameter, which is covered with whitish fibres. The surface has a wrinkled and furrowed texture. It may have a lilac tinge when young. It is convex initially before expanding and flattening with a boss (umbo) in the centre. The stipe is 4–12 cm (1+1⁄2–4+3⁄4 in) long and 1–2.2 cm (1⁄2–3⁄4 in) thick; it is slightly swollen at the base, and whitish to beige with a noteworthy whitish ring, which is initially attached to the cap. The partial veil is a key identifying feature of the mushroom. The spores give an ochre-brown spore print. The warty almond-shaped spores measure 10–13 μm long by 8–9 μm wide. The flesh is cream-coloured and the flavor mild.

Similar species. Similar-looking North American species include Agrocybe praecox, which lacks the wrinkled cap and is found in cultivated areas, and Phaeolepiota aurea, which has a powdery-granular surface. Members of the Cortinarius subgenus Telamonia have thin rings and C. corrugatus has none, with a wrinkled cap. In central Europe, old specimens could be mistaken for the highly poisonous Inosperma erubescens in summer, and young mushrooms for the inedible Cortinarius traganus, although the latter is readily distinguished by its unpleasant odour.

C. caperatus is found across northern Europe, mainly in Scandinavia, where it is common, although it is uncommon in Denmark and Iceland. In the British Isles it is uncommon outside the Scottish Highlands and the New Forest. It has been classified as vulnerable in Germany and Great Britain and endangered in the Netherlands. C. caperatus had become less common in the vicinity of Salzburg in Austria between 1937 and 1988, thought due to picking. It is widely found in northern parts of North America, as far south as Mendocino County on the west coast. It is uncommon in California. C. caperatus is a rare component of subarctic areas of western Greenland. The fungus also grows in temperate Asia, having been recorded growing with bilberry near oriental beech (Fagus orientalis) and fir near Pamukova in the Marmara Region of Turkey. It is also found in boggy areas of the taiga (boreal pine forest) in western Siberia. Fruiting bodies sprout from August to October in conifer and beech woods, as well as heather (often close by sphagnum) in Scotland. It is mycorrhizal but non-selective in its hosts. Mushrooms appear from September to November in North America, and July and August in Alaska. It prefers acidic and sandy soils and avoids chalky ones, and may be found in the same habitats as bay bolete (Imleria badia), brown roll-rim (Paxillus involutus), and chanterelles. …

C. caperatus is a highly regarded edible mushroom with a mild to good flavour. It is said to mix well with stronger-flavoured fungi such as chanterelles, boletes, brittlegills or milk-caps. The mushroom can have a faintly bitter taste if eaten raw, but a pleasant nutty flavour when cooked. It can readily be dried for later use, such as adding to soups and stews. It is sold commercially in Finland, and is a popular target of foragers in many parts of Europe. Mycologist David Arora recommends discarding the tough stipes.