inky cap, (genus Coprinus), genus of about 350 cosmopolitan mushroom species. Inky caps are so named for the disintegration of the mushroom cap into an inklike liquid following spore discharge. The inklike liquid has been used for writing. Inky caps grow on wood and dung. The caps of C. atramentarius and C. comatus (shaggy mane, or shaggy cap) are edible when young, before the gills turn black.
See also list of fungi