Inky Caps

Small mushrooms called ink-caps belonging to the genus Coprinus (also seen as Coprinellus)  are distinctive for a couple of reasons. At least one species from this group produces a conspicuous mycelial mat that is orange-brown, “fuzzy” and readily visible on surface of the substrate (usually dead wood). The mycelia of nearly all other mushrooms are entirely embedded in the substrate in which the mushroom occurs and if visible, appear as very fine white strands.

Immature fruiting bodies of Coprinus radicans (pointing downward).  Note the orange mycelial mat at the base of the mushrooms which are about 1 cm in height. The stipes are too short to be visible from this angle at this stage.








The caps may be brown, white or buff and establish on dead wood. They also may  appear indoors, colonizing wood in moist environments like basements. The expanding mushroom fractures the veil leaving rows of tiny veil fragments on the cap while the white stipe elongates. Then, within a day or so the gills comprising most of the cap liquefy, forming a black, inky fluid which contains the spores and provides the mechanism for dispersing them. At this stage the mushroom looks nothing like the younger stage and might be mistaken for a different species.

The mushrooms are elevated on long stipes for about a day or so as they approach the deliquescence stage.

In this close-up, the caps have opened and blackened but haven’t yet liquefied. Remnants of the young  fruiting body persist on the caps.


The liquidification process is called deliquescence and some specialists have placed all deliquescent fungi in the genus Coprinus although there is not universal agreement on this. After the fruiting bodies are long gone, one or more new ones may appear on the same piece of wood and the distinctive mycelium may persist on the substrate for days, far outlasting individual mushrooms. The mushrooms themselves persist no longer than 3 or 4 days from first appearance until deliquescence.

In the latest stage pictured, the caps have deliquesced and are watery and black to the touch but the stipes  are intact so the mushroom has not yet collapsed.





Note that all photographs were taken of mushrooms  found in my yard growing on a dead oak branch.