What You Should Know
Cortinarius hemitrichus is a basidiomycete mushroom of the genus Cortinarius. Young mushrooms are characterized by their brown cone-shaped caps covered with dense white fibrils. It grows in both deciduous and coniferous forests, often beneath birches, scattered throughout Europe and North America.
This mushroom is generally regarded as inedible and should not be gathered for eating. Some Cortinarius species contain the toxin orellanine, which if eaten destroys human kidneys and liver.
Other names: Frosty Webcap.
Cortinarius hemitrichus Mushroom Identification
The cap is 2–4.5 cm (0.8–1.8 in) wide, convex, with a flattish or more pointed umbo (occasionally the umbo may be lacking), watery date brown, hygrophanous. In damp weather, the cap surface is almost chestnut brown in young specimens, in dry weather grayish-brown to tan brown. The surface is soon silky and the margin almost white from floccose, white fibrils (these are easily washed off by rain), otherwise only very slightly whitish fibrillose, finally even bare. When the tip of the stem is hollow, the cap is thinly fleshy and quite tough.
The gills are distantly spaced, grayish-earthy, then ochraceous ferruginous, later almost cinnamon, broadly emarginate (notched), 5–8 mm (0.2–0.3 in) broad, slightly ventricose, with a lightly scalloped edge.
The stem is cylindrical, quite slender, usually slightly crooked, 5–6 cm (2.0–2.4 in) long and 3–6 mm (0.12–0.24 in) thick, light brown inside with thin, winding fibers, then eventually hollow. It is white, covered with silky fibrils on the surface, often with an ephemeral white zone in the middle which may be poorly developed, otherwise pale dirty gray, with steel gray to violet tinge at the apex.
The flesh is watery brown in damp weather, then much lighter, whitish with a brownish tinge. It has a mild taste and is almost without odor. However, it is inedible.
The spore dust is rusty-brown. The spores are egg-shaped, obliquely pointed, yellowish rusty brown, with fine warts and dots on the surface, and measure 8–9 by 4.5–5 μm.
Cortinarius flexipes, the Pelargonium Waxcap, is similar but is distinguished by its strong odor of pelargoniums
Cortinarius hemitrichus Taxonomy and Etymology
When in 1801 Christiaan Hendrik Persoon described this webcap he gave it the scientific name Agaricus hemitrichus.
The Swedish mycologist Elias Magnus Fries, in 1838, transferred this species to the genus Cortinarius, whereupon it assumed its currently-accepted scientific name Cortinarius hemitrichus.
Agaricus hemitrichus Pers., is a synonym of Cortinarius hemitrichus.
The generic name Cortinarius is a reference to the partial veil or cortina (meaning a curtain) that covers the gills when caps are immature. In the genus Cortinarius most species produce partial veils in the form of a fine web of radial fibers connecting the stem to the rim of the cap rather than a solid membrane.
The specific epithet hemitrichus may come from the prefix hemi- meaning half and -trichus meaning hairy (or fibrous). If you believe that this is an incorrect interpretation we would appreciate your help to correct it.
Photo 1 - Author: Jerzy Opioła (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 2 - Author: Thomas Pruß (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 3 - Author: Jerzy Opioła (Creative Commons Attribution-Share Alike 4.0 International)