Cortinarius hinnuleus (Sowerby) Fr. - Earthy Webcap

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Cortinariaceae

Distribution - Taxonomic History - Etymology - Toxicity - Identification - Reference Sources

Cortinarius hinnuleus is one of the many brown webcaps found under broadleaf trees. The identification of this undistinguished mushroom is eased somewhat by its habitat needs: damp woodlands with willow or poplar trees.

Distribution

An occasional species in Britain and Ireland, the Earthy Webcap is also found throughout much of mainland Europe and in parts of North America.

Taxonomic history

When in 1798 British naturalist James Sowerby (1757-1822) described the Earthy Webcap he gave it the binomial scientific name Agaricus hinnuleus. (Most gilled fungi were initially placed in a giant Agaricus genus, now redistributed across many other newer genera.) It was the great Swedish mycologist Elias Magnus Fries who, in 1838, transferred this species to the genus Cortinarius, whereupon it assumed its currently-accepted scientific name Cortinarius hinnuleus.

Synonyms of Cortinarius hinnuleus include Agaricus hinnuleus Sowerby, Lepiota helvola Gray, and Cortinarius hinnuleus var. radicata Rob. Henry.

Etymology

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 fibres connecting the stem to the rim of the cap rather than a solid membrane.

The specific epithet hinnuleus means tawny-cinnamon coloured (the colour of a young hide or fawn).

Toxicity

This mushroom is generally regarded as poisonous and it should not be gathered for eating. (Some brownish Cortinarius species contain the toxin orellanine, which if eaten destroys human kidneys and liver.)

Identification guide

	Cap Young caps are bell shaped and dark ochre brown; the pale margin is covered in a whitish cobwebby veil. Mature caps, which usually have a shallow umbo, are hygrophanous, drying out to a mid ochraceous brown; 2.5 to 6cm in diameter.
	Gills Initially pale buff with a violaceous tinge, turning tawny brown as the spores mature, the gills are adnate and crowded. The cortina covering young gills is white. Stem Mid brown, the lower part covered in white silky veil remnants; there is usually a distinct white ring zone; 5 to 12mm diameter and 3 to 10cm tall. Stem flesh white tinged with brown, in young stems flushed violaceous towards the apex.
	Spores Ellipsoidal, 7-8 x 4-4.75µm, with a minutely roughened surface. Show larger image Spores of Cortinarius hinnuleus, Earthy Webcap  X  Spore print Rusty brown.
Odour/taste	Taste initially mild then slightly bitter; odour slight, of radish.
Habitat & Ecological role	Mycorrhizal, in deciduous woodland with willows and poplars.
Season	August to November in Britain and Ireland.
Similar Species	Cortinarius flexipes, the Pelargonium Waxcap, is distinguished by its strong odour of pelargoniums (house plant 'geraniums'!)

Reference Sources

Fascinated by Fungi, 2nd Edition, Pat O'Reilly 2016, reprinted by Coch-y-bonddu Books in 2022.

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

Fungi of Switzerland Agarics, part 3: Cortinariaceae, Breitenbach, J., Kränzlin, F.

British Mycological Society, English Names for Fungi.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi.

Acknowledgements

This page includes pictures kindly contributed by Simon Harding.

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