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Kuehneromyces mutabilis

[ Basidiomycota > Agaricales > Strophariaceae > Kuehneromyces . . . ]

by Michael Kuo

Among the 200 or so pholiotoid mushrooms that have been described for North America, Kuehneromyces mutabilis is fairly distinct. 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.

Similar mushrooms include Galerina marginata, with a stem that is not scaly and a cap that turns red with KOH; Hypholoma capnoides, with a smooth stem and gills that become grayish brown to purplish brown; and several species of Armillaria, with white spore prints--especially Armillaria nabsnona, which grows on the wood of alders (I have found Kuehneromyces mutabilis on alder wood and on conifer wood).

Although Kuehneromyces mutabilis is frequently treated as a species of Pholiota, DNA studies that have included the species (e.g. Matsumoto et al. 2003, Jacobsson & Larsson, 2007) support the idea that it belongs apart from Pholiota in Kuehneromyces, which was established by Singer & Smith (1946) with Kuehneromyces mutabilis as the representative, or "type," species.

Pholiota mutabilis and Galerina mutabilis are synonyms.


Ecology: Saprobic; growing in clusters (rarely growing alone) on the wood of hardwoods or conifers; spring, summer, and fall (and over winter in warm climates); widely distributed and common in montane western North America, and occasionally reported from the Appalachian Mountains. The illustrated and described collections are from Colorado.

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.

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.

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.

Flesh: Whitish; unchanging when sliced.

Odor and Taste: Not distinctive.

Chemical Reactions: KOH negative on cap surface.

Spore Print: Cinnamon brown.

Microscopic Features: Spores 6-8 x 4-5 µm; subellipsoid to sublacrymoid; with a well developed apical pore; smooth; pale brown to brownish golden in KOH. Cheilocystidia 35-50 x 7.5-12.5 µm; lageniform with a long neck and a subcapitate to subclavate apex; thin-walled; smooth; hyaline in KOH. Pleurocystidia not found. Pileipellis an ixotrichoderm; elements 2.5-7.5 µm wide, smooth, hyaline to brownish or golden in KOH. Clamp connections present.

REFERENCES: (Schaeffer, 1774) Singer & A. H. Smith, 1946. (Fries, 1821; Saccardo, 1887; Overholts, 1927; Smith & Hesler, 1968; Smith, 1975; Smith, Smith & Weber, 1979; Arora, 1986; Jacobsson, 1989; Phillips, 1991/2005; Lincoff, 1992; Barron, 1999; Matsumoto et al. 2003; Roody, 2003; Miller & Miller, 2006; Jacobsson & Larsson, 2007; Kuo & Methven, 2014.) Herb. Kuo 08150713, 08131502.

Further Online Information:

Kuehneromyces mutabilis in Singer & Smith (1946)
Pholiota mutabilis in Smith & Hesler (1968)
Kuehneromyces mutabilis at Roger's Mushrooms

This site contains no information about the edibility or toxicity of mushrooms.


Kuehneromyces mutabilis

Kuehneromyces mutabilis

Kuehneromyces mutabilis

Kuehneromyces mutabilis

Kuehneromyces mutabilis

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Kuo, M. (2017, January). Kuehneromyces mutabilis. Retrieved from the MushroomExpert.Com Web site: