A number of potentially poisonous mushrooms are superficially similar. Coprinopsis atramentaria
, which is toxic when ingested with alcohol, also grows in clusters at the base of trees and also turns inky in age. It differs in that the cap is more greyish and lacks salt-like granules when young. The less common Coprinopsis romagnesiana
differs in that the cap is covered with darker brown appressed scales and lacks granules when young. It is toxic when consumed with alcohol. Coprinellus domesticus
, of unknown edibility, differs in that the young cap is dotted with whitish scales and the fungus forms a mat of orange, hair-like fibers on the decaying log that it grows from. The less common Coprinellus flocculosus
, of unknown edibility, differs in that the young cap is covered with tufts of whitish, felty warts. The edible Coprinellus disseminatus
is smaller (under 2 cm broad), lacks granules on the cap, and does not become inky when old.