Mycena epipterygia (Scop.) Gray - Yellowleg Bonnet

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

Distribution - Taxonomic History - Etymology - Identification - Culinary Notes - Reference Sources

Many of the bonnet fungi are difficult to identify with confidence, but the greenish-yellow stems of Mycena epipterygia are a distinguishing feature of this delicate little autumn fungus, which seems to be equally at home in woodlands or in grassland.

Distribution

This tiny gregarious bonnet fungus is common and widespread in Britain and Ireland as well as in most of mainland Europe. This species is also recorded in parts of North America.

Taxonomic history

When in 1772 Italian mycologist Giovanni Antonio Scopoli described this little bonnet mushroom he gave it the name Agaricus epipterygius. (In the early years of fungal taxonomy most of the gilled mushrooms were included initially in the genus Agaricus, the contents of which has since largely been redistributed across several newer genera.) The currently accepted scientific name Mycena epipterygia dates from 1821, when the British mycologist Samuel Frederick Gray (1766 - 1828) transferred this species to the genus Mycena.

The Yellowleg Bonnet has accumulated quite an array of synonyms including Agaricus epipterygius Scop., Agaricus flavipes Sibth., Agaricus nutans Sowerby, Agaricus citrinellus Pers., Mycena epipterygia var. epipterygia (Scop.) Gray, Mycena flavipes (Sibth.) Gray, Agaricus plicatocrenatus Fr., Mycena citrinella (Pers.) P. Kumm., Mycena plicatocrenata (Fr.) Gillet, and Mycena splendidipes Peck.

Etymology

The specific epithet epipterygia comes from the prefix epi- meaning upon and pterugion meaning 'resembling a (small) wing'. Something of a flight of fancy, perhaps? It is reported to mean 'on ferns', and these bonnet mushrooms do indeed grow sometimes on the rotting remains of ferns.

The common name Yellowleg Bonnet is self explanatory... until you come across a group of these mushrooms where, like those shown on the left, the dominant colour of the stems is green!

Although Mycena epipterygia is most often seen on woodland floors and (as shown on the left) less frequently in grassland, particularly beside hedgerows and woods, I have also seen a group of these pretty little bonnet mushrooms growing from a twig on a standing dead pollard (probably Hazel) at head height in damp mixed woodland. It's certainly worth looking up as well as down when in search of Mycena species!

Identification guide

	The translucent nature of these tiny bell cap fungi together with their long, lemon-yellow to greenish stems make them relatively easy to find despite their small size.
	Cap 1 to 3cm in diameter when fully mature, the fragile caps are mid- to dark olive-brown with a paler edge. Initially bell-shaped, the striate caps expand to become convex. In some instances the cap flattens and the margin turns upwards slightly, revealing the gills. The cap flesh is white and thin above a translucent flexible pellicle (cap skin) which can easily be peeled off - a helpful identification feature.
	Gills Adnate or slightly decurrent, the gills are white or cream with a slight pink tinge when fully mature.
	Stem Relative to the cap size, these bonnet mushrooms have unusually long, fragile stems. Just 1 to 3mm in diameter, the smooth, lemon-yellow viscid stems are untapering and 3 to 7cm tall with no stem ring. The stem flesh is almost white.
	Cheilocystidia Cheilosystidia (cystidia on gill edges) are up to 35µm long and extremely misshapen with irregular outgrowths. Pleurocystidia (cystidia on the gill faces) are absent. Show larger image Cheilocystidia of Mycena epipterygia  X
	Spores Broadly ellipsoidal to cylindrical, smooth, 8-11 x 4-6µm; amyloid. Show larger image Spores of Mycena epipterygia, Yellowleg Bonnet  X  Spore print White or very pale buff.
Odour/taste	Faintly mealy odour; no distinctive taste.
Habitat & Ecological role	Saprobic, mostly in coniferous woodland but a variety of this species is also found in damp grassland and moss.
Season	August to November in Britain and Ireland.
Similar species	There are many other small, bell-shaped fungi in the Mycena genus; however, the lemon stem of this striking species helps to distinguish it from the other common species found in similar habitats.

Culinary Notes

These little mushrooms are reported to be edible, but they are so insubstantial that they are definitely not worth collecting to eat.

Reference Sources

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

Penny Cullington, (Oct. 2013). British Mycenas - Brief Descriptions.

Giovanni Robich, (2003). Mycena d'Europa; Associazione Micologica Bresadola ; Vicenza : Fondazione Centro Studi Micologici.

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.

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