What You Should Know
Cortinarius triumphans is a basidiomycete mushroom of the genus Cortinarius found in Europe. It has a yellowish cap darker in the center and paler on the edges. The stipe is thick and swollen at the base and is white up top and yellow lower down and bears the tan or brown remnants of the veil. The adnate gills, which are hidden by cream or white veil when young, are cream or lilac early on and darken with the spores, which give a rusty colored spore print. The flesh is cream-colored and the taste mild.
It is regarded as edible by some authorities, although others call it suspect and it resembles inedible species.
Very young fruitbodies could be mistaken for the Larch Bolete Suillus grevillei, but once the caps open there is no risk of such confusion because the Birch Webcap is a gilled mushroom whereas the Larch Bolete has tubes and pores on the undersides of its caps.
Cortinarius triumphans is generally regarded as 'suspect' and may contain dangerous toxins; they should not be gathered for eating.
Other names: Birch Webcap, Yellow Girdled Webcap.
Cortinarius triumphans Mushroom Identification
Slimy in wet weather, remaining sticky; 5 to 12cm in diameter; hemispherical to convex at first, expanding until almost flat or occasionally shallowly umbonate but retaining a downturned or slightly incurved margin; golden yellow with a slightly browner center, the cap surface is radially fibrillose and sometimes becomes slightly scaly towards the center when fully mature. Cap and stem flesh are pale cream.
The adnate-emarginate gills are raggedly toothed, close and initially creamy-white with a faint lavender tinge, turning ochre and then becoming stained rusty brown as the spores mature. A whitish cortina (cobweb-like partial veil) covers the gills of very young caps.
The dry (not slimy) stems are 1.2 to 2.5cm in diameter and 7 to 12cm tall; clavate, sometimes with a basal bulb.
The surface of the stipe is whitish near the apex and pale yellow below, with two or more tan-colored prominent ring zones.
Ellipsoidal to amygdaloid (almond-shaped), 10-12.5 x 5.5-7μm; inamyloid.
Odor and Taste
Odor not distinctive; taste mild.
Habitat & Ecological Role
Ectomycorrhizal, in broadleaf and mixed woodlands with birches, Beech and occasionally other broadleaf trees.
Cortinarius triumphans Look-Alikes
Has a yellow cap but its gills are bluish when young.
Has a darker, dry cap.
Cortinarius triumphans Taxonomy and Etymology
This striking webcap is a member of the Cortinarius sub-genus Phlegmacium. The Birch Webcap was described in 1838 by Elias Magnus Fries. who gave it the binomial scientific name Cortinarius triumphans which remains its generally accepted scientific name.
Until recently this webcap was most often recorded as Cortinarius crocolitus Quél., which is now considered to be a synonym of Cortinarius triumphans. (I found the specimen shown here under birches on a roadside in central France.)
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.
Just as you might expect, the specific epithet triumphans means triumphant. Although spotting these large, bright-yellow mushrooms is hardly a triumph of observation, I do feel 'joyful and triumphant' when I stumble across the Birch Webcap.
Photo 1 - Author: Dragonòt (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 2 - Author: Stu's Images (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 3 - Author: Nikolay Bulykin (1992–) (Creative Commons Attribution-Share Alike 4.0 International)
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