Kuehneromyces mutabilis (Schaeff.) Singer & A.H. Sm. - Wood Tuft

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Agaricales

Other common names for this attractive species are Brown Stew Fungus and Two-toned Pholiota, so-called because the hygrophanous cap is a shiny cinnamon-orange when wet but it dries a much lighter tan colour.

This attractive, edible fungus appears throughout the year, often in large tufts, on stumps of hardwood (broadleaf) trees. In older field guides you may find it recorded under the scientific synonyms Galerina mutabilis (Schaeff.) P.D. Orton or Pholiota mutabilis (Schaeff.) P. Kumm.

Occasionally these colourful little mushrooms appear to be growing on the forest floor, but in my experience if you scrape away the surface layer of leaf litter and twigs you will find, as in this picture taken in Finland by Lena Mickelsson, that they are feeding saprobically on buried timber.

Jacob Christian Schaeffer first described this species in 1762, calling it Agaricus mutabilis. (Most of the gilled mushrooms were included initially in the genus Agaricus!) The present scientific name Kuehneromyces mutabilis dates from 1946, when Rolf Singer and Alexander Hanchet Smith (1904 - 1986) established the Kuehneromyces genus of wood tuft fungi. (I understand that the genus name is in reference to American mycologist Calvin C Kuehner (1922 - 2011).

Kuehneromyces mutabilis is the type species of the genus Kuehneromyces.

Identification Guide

	Cap 3 to 8cm in diameter, convex becoming flattened with a broad umbo; bright tan, drying out to pale ochre from the centre and giving a two-toned (zonate) appearance. The cap flesh is pale tan and quite thin.
	Gills Adnate and crowded, the gills are pale ochre at first and become cinnamon as the spores mature. Stem Pale and smooth above the ragged stem ring; fibrous, scaly and dark tan below, graduating to almost black at the base. 5 to 10mm in diameter and 3 to 8cm tall; usually curved. The flesh of the solid stem is pale tan at the apex, graduating to dark brown at the base.
	Spores Broadly ellipsoidal, smooth, 5.5-7.5 x 4-5um; with an apical germ pore. Spore print Reddish-ochre to dark cinnamon brown.
Odour/taste	Not distinctive.
Habitat	Saprobic, on stumps, felled trunks and logs of broad-leaf trees, particularly birch.
Season	Throughout the year, but most plentiful in summer and autumn.
Occurrence	Very common throughout Britain and Ireland, Wood Tuft fungi are also common throughout mainland Europe and in North America.
Similar species	Flammulina velutipes, commonly called Velvet Shank, has a darker, velvety stem and leaves a white spore print. Galerina marginata is very similar and sometimes only separable for certain by microscopic examination; it is deadly poisonous.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2011

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 and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.