Kuehneromyces mutabilis

What You Should Know

Kuehneromyces mutabilis is a widespread edible mushroom. Widely distributed in northern Europe, Asia and North America.

This attractive fungus appears throughout the year, often in large tufts, on stumps of hardwood (broadleaf) trees. It has a bald, "hygrophanous" cap—meaning it changes color markedly as it dries out, going from orangish brown to yellowish, often passing through a two-toned stage. The stem is scaly and usually features a well-developed ring.

Like other pholiotoid mushrooms, it grows on wood, has a brown spore print, and features gills that are attached to the stem. Identifying microscopic features include the small spores with a well-developed pore and small cheilocystidia.

In older field guides you may find it recorded under the synonyms Galerina Mutabilis or Pholiota Mutabilis.

Other names: Sheathed Woodtuft, Brown Stew Fungus, Two-toned Pholiota, Stockschwämmchen (German).

Kuehneromyces mutabilis Mushroom Identification

1. Ecology

   Saprobic; growing in clusters (rarely growing alone) on the wood of hardwoods or conifers; spring, summer, and fall (and overwinter in warm climates); widely distributed and common in montane western North America, and occasionally reported from the Appalachian Mountains.

2. Cap

   3–5.5 cm; convex, becoming broadly convex or nearly flat; sticky when fresh; bald or, when young, with scattered whitish to yellowish fibrils; tawny to orangish brown, changing color markedly as it dries out and fading to yellowish or brownish (often passing through a two-toned stage); the margin finely lined when moist.

3. Gills

   Attached to the stem by means of a notch; close; short-gills frequent; whitish to pale tan when young, becoming cinnamon brown; at first covered by a whitish to pale tan partial veil.

4. Stem

   5–9 cm long; up to 1 cm thick; tapered to the base; dry; silky near the apex; with a fairly persistent whitish ring that features an orangish brownish edge and eventually becomes orangish-brown overall - or with merely a ring zone; whitish becoming brown from the base up; covered with small, whitish to brownish scales.

5. Flesh

   Whitish; unchanging when sliced.

6. Spore Print

   Cinnamon brown.

Kuehneromyces mutabilis Medicinal Properties

1. Antiviral activity

   The title of Mentel and associates’ paper (1994) suggests that the two-toned pholiota has some anti-viral activity against influenza virus.

2. Antitumor activity

   Polysaccharides extracted from the mycelial culture of K. mutabilis and administered intraperitoneally into white mice at a dosage of 300 mg/kg inhibited the growth of Sarcoma 180 and Ehrlich solid cancers by 100% and 90%, respectively (Ohtsuka et al., 1973).

Kuehneromyces mutabilis Taxonomy and Etymology

Jacob Christian Schaeffer described this species in 1762, calling it Agaricus mutabilis. 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.

Kuehneromyces mutabilis is the type species of the genus Kuehneromyces.

The genus name is in honor of American mycologist Calvin C Kuehner (1922 - 2011). The specific epithet mutabilis means changeable, and this is a reference to the very variable coloring of the caps depending on how damp they are.

Sources:

Photo 1 - Author: Syrio (Creative Commons Attribution-Share Alike 4.0 International)

Photo 2 - Author: Holger Krisp (Creative Commons Attribution 3.0 Unported)

Photo 3 - Author: Strobilomyces (Creative Commons Attribution-Share Alike 3.0 Unported)

Photo 4 - Author: Jerzy Opioła (Creative Commons Attribution-Share Alike 3.0 Unported)