Family: Psathyrellaceae
Mica Cap Mushroom (Coprinellus micaceus) is a delicate, clustered inky-cap mushroom that commonly fruits from decaying hardwood, buried roots, stumps, or woody debris. Young caps are honey-brown to pale tan and often carry tiny mica-like granules that can sparkle in fresh specimens, giving the species its common name.
For representative images and visual context, see the page: Mica Cap Mushroom in the Gallery section.
Description
Coprinellus micaceus is recognized by:
- Growth form: gregarious to densely clustered mushrooms, often in small tufts or troops
- Cap: oval to bell-shaped when young, expanding with age; honey-brown, amber-tan, or pale buff
- Cap surface: finely grooved or pleated, especially toward the margin; fresh young caps may show tiny glistening granules
- Margin: strongly striate, often becoming gray to black as the gills mature
- Gills: crowded; pale at first, becoming gray, then dark purplish-black to black
- Stem: slender, white to pale, fragile, smooth to faintly silky, without a ring
- Spore print: black to very dark brown-black
The fruiting bodies are short-lived and can change quickly after rain or during warm weather. The glistening cap granules are most visible on fresh, young caps and may disappear after rain, handling, or age.
Substrate and Habitat
Typical substrates and settings include:
- Decaying hardwood stumps, buried roots, and woody debris
- Soil that appears open but contains buried wood
- Woodland edges, parks, yards, trailsides, and disturbed hardwood areas
Notes may include:
- Often fruits in clusters from the same hidden wood source
- Common after rain during spring and fall, but can appear through much of the growing season
- Frequently found near broadleaf trees where old roots or buried wood remain
Identification
Key features for field diagnosis:
- Clustered habit: several to many mushrooms arising together from wood or buried roots
- Cap color: warm honey-brown to buff, often darker toward the center
- Cap texture: delicate, pleated, and often dusted with mica-like granules when fresh
- Gills: darken from pale to gray-black or black as spores mature
- Stem: thin, white, fragile, and ringless
- Spore print: black to dark brown-black
This species is separated from many similar inky caps by the combination of clustered growth on wood or buried wood, small bell-shaped tan caps, pleated margins, and the presence of glittering cap granules on fresh specimens. The granules are useful when present but should not be treated as the only identifying feature because they are easily washed away.
Similar species include other small inky caps in Coprinellus and related genera. Coprinellus disseminatus is usually smaller and forms larger, dense troops with paler caps. Coprinellus domesticus may show orange-brown ozonium on nearby wood. Larger gray inky caps such as Coprinopsis atramentaria differ in size, shape, and overall coloration.
Ecology and Notes
- Saprobic, helping break down dead hardwood and buried woody material
- Fruiting bodies are fragile and may collapse or darken quickly as the gills mature
- The same buried wood source may produce repeated clusters after favorable rain
- Photographs are most useful when they show cap surface, gill color, clustered growth, and substrate context
- This page is intended for photographic and field-identification notes, not for edibility guidance
References
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iNaturalist taxon page https://www.inaturalist.org/taxa/56310-Coprinellus-micaceus
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MushroomExpert.com https://www.mushroomexpert.com/coprinellus_micaceus.html
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MycoBank taxon page https://www.mycobank.org