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Coprinellus micaceus

[ Basidiomycetes > Agaricales > Psathyrellaceae > Coprinellus . . . ]

by Michael Kuo

This common and beautiful mushroom is widely distributed in North America. It grows in clusters on decaying wood--though the wood may be buried, causing the mushrooms to look terrestrial. It can be distinguished from similar coprinoid mushrooms by the fine, mica-like granules that adorn the fresh caps (though rain will frequently wash the granules away). It is variable in color, but typically some version of honey brown or amber.


Ecology: Saprobic, growing in clusters on decaying wood (the wood may be buried, causing the mushrooms to appear terrestrial); spring, summer, and fall (sometimes in winter); frequently urban, but also found in woods; widely distributed in North America.

Cap: 2-15 cm, oval when young, expanding to broadly convex or bell-shaped, sometimes with a curled up and/or tattered margin; honey brown, tawny, amber, or sometimes paler; becoming paler with age, especially towards the margin; buttons covered with mica-like granules which frequently wash off with rain or dew; the margin lined or grooved, usually halfway towards the center or more.

Gills: Attached to the stem or free from it; pale, becoming brown, then black; deliquescing (turning to black "ink") but usually not completely; close or crowded.

Stem: 2-8 cm long; 3-6 mm thick; equal; smooth to very finely hairy or granulated; white; fibrous; hollow.

Flesh: White to pale throughout; thin; soft.

Odor and Taste: Not distinctive.

Spore Print: Black.

Microscopic Features: Spores 7-11 x 4-7 µ; subelliptical to mitriform; smooth; with a central pore. Basidia 4-spored; surrounded by 3-6 brachybasidia. Pleurocystidia elliptical to ovoid or subclavate; up to 150 x 70 µ. Cheilocystidia similar. Pileipellis an epithelium. Veil elements subglobose to cylindric; chained; up to 70 µ wide. Caulocystidia lageniform; up to 100 µ long.

The macrofeature description above matches several official species, all of which are commonly called "Coprinus micaceus" in North American field guides. Kees Uljé's key to the micaceus cluster contains 5 taxa from around the world, separated on the basis of spore and caulocystidia morphology (among other things). Officially, Coprinellus micaceus should have caulocystidia (and, therefore, a very finely pruinose stem surface) and mitriform (shaped like a bishop's hat) spores. Coprinellus truncorum, by "contrast," has a smooth stem (consequently no caulocystidia) and more elliptical spores. I have made collections that seemed to share features from both of these taxa. Preliminary DNA results from Ko and collaborators (2001) indicate the possibility that Coprinellus micaceus and Coprinellus truncorum are genetically identical--though this only becomes evident in Keirle and collaborators (2004), who reveal that two of the "Coprinellus micaceus" specimens tested by Ko and collaborators were initially identified as Coprinellus truncorum.

Coprinus micaceus is a synonym.

REFERENCES: (Bulliard, 1786) Vilgalys, Hopple & Jacq. Johnson, 2001. (Saccardo, 1887; Kauffman, 1918; Smith, 1975; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Horn, Kay & Abel, 1993; Breitenbach & Kranzlin, 1995; Evenson, 1997; Barron, 1999; Roody, 2003; Uljé, 2003; Keirle et al., 2004; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 05169510, 04150301, 04290303.

Further Online Information:

Coprinus micaceus at Kees Uljé's Coprinus site
Coprinellus micaceus at MykoWeb
Coprinus micaceus at Roger's Mushrooms


Coprinellus micaceus

Coprinellus micaceus

Coprinellus micaceus

Coprinellus micaceus
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Coprinellus micaceus

Coprinellus micaceus

Coprinellus micaceus

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Kuo, M. (2008, February). Coprinellus micaceus. Retrieved from the MushroomExpert.Com Web site: