Public Description of Coprinellus micaceus (Bull.) Vilgalys, Hopple & Jacq. Johnson

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Name: Coprinellus micaceus (Bull.) Vilgalys, Hopple & Jacq. Johnson
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 Draft For 2008/2009 Eol University Species Pages Initiative By Melinda Mundt (Private)
 Draft For Macrofungi Of The Pacific Northwest By Chaelthomas (Private)

Description status: Unreviewed

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Psathyrellaceae

General Description:

It is commonly called the Mica Cap. C. micaceus is one of the inky caps, so called because of the way the gills digest themselves (deliquesce) to release spores, leaving a black residue that resembles ink.
The pileus of C. micaceus is oval shaped when the mushroom is young and becomes convex as it ages. The size ranges from 2-5 cm (.75-2 in). Small, shiny white, granular scales can be found on the pileus when the mushroom is young. The name of the mushroom derives from these granular scales, which look like the mineral mica (Also, “mica” in Latin means shiny). The pileus ranges in color from yellowish to honey brown to amber.
Gills are attached to nearly free and very crowded. The color of the gills starts as white to very light gray when young and becomes purple to black and inky with age as the gills deliquesce.
The stipe of this mushroom ranges from 2.5-8 cm (1-3 1/8 in) long and 2-5 mm (1/8-1/4 in) thick. The stipe is white, smooth, and hollow.
The spore print of this mushroom is black. The spores are sized 7-10 um X 4-5 um. Microscopically, the spores are grayish to pale black, elliptical and smooth, with an apical pore.
C. micaceus can be found scattered or densely packed in groups. This mushroom grows on decaying wood. It is a very common mushroom to find. C. micaceus grows most commonly from April to October. It can be found in both urban lawns and forests.
This mushroom is thought to be edible but mostly flavorless.

Also known as Coprinus micaceus. The genus Coprinus was split up based on many microscopic features.

Diagnostic Description:

This mushroom is one of the inky caps. Gills self-digest to release the spores, producing an inky substance.
The most distinguishing feature about this mushroom is the shiny, mica-like granules on its pileus. No other inky cap mushroom has this feature. The granules can sometimes get off the mushroom, however. In this case, the yellowish color of the cap is an important factor, along with the small size of the mushroom.


This mushroom can be found throughout most of North America. It is known to be widespread throughout the United States and can be found fruiting from spring until fall. This mushroom can also be found commonly in Europe.


This mushroom is a saprophyte. It can be found growing on decaying wood. C. micaceus can be found in numerous places. It grows commonly on decaying wood in forests. It can also be found in lawns, growing on buried decaying wood or old dead stumps.

Look Alikes:

Coprinopsis atramentarius also fruits in dense clusters, but its cap is brown, and it is a larger mushroom than C. micaceus. The more common Coprinus comatus is much larger and scalier.


It is an edible mushroom, if eaten when young, before gills deliquesce.
Some compounds have been extracted from this mushroom that are thought to have antimicrobial properties.


Bessette, A.E., A.R. Bessette, & D.W. Fischer. Mushrooms of Northeastern North America. 1997. Syracuse, NY: Syracuse University Press, 2002.

Kuo, M. “Coprinellus micaceus.” Feb. 2008. Accessed Dec. 8 2008.

Sasata, R. “Coprinellus micaceus.” Medicinal Mushrooms. Aug. 17 2008. Accessed Dec. 8 2008.

Wood, M. & F. Stevens. “Coprinellus micaceus.” MykoWeb. 2007. Accessed Dec. 8 2008.


“Common Name: Mica Cap / Glistening Inky Cap”

Also known as Coprinus micaceus.

Melinda Mundt
UW-La Crosse Mycology
December 2008

Description authors: Tom Volk, Melinda Mundt (Request Authorship Credit)
Description editors: Nathan Wilson, IntoTheFlames