Common Name: none
Synonyms: Coprinus friesii Quélet; Coprinus rhombisporus Orton
Cap 0.5-1.5 cm broad, at first ellipsoid, then obtuse-conic, eventually broadly-conic to nearly plane; margin incurved, becoming decurved, radially split, and revolute at maturity; surface striate to near the disc, white to ash-grey, darker-grey in age, covered with small, pallid to tan-colored, evanescent scales, concentrated at the disc; context membranous, weakly deliquescent; odor not distinctive; taste untried.
Gills free, close, relatively narrow, pale-grey, occasionally forked, the faces light-grey, edges blackish from maturing spores; lamellulae in up to three series.
Stipe 1.5-4.0 cm long, up to 1.0 mm thick, fragile, round, hollow, equal except swollen at the base; surface white, glabrous to innately striate, finely tomentose at the base; partial veil absent.
Spores 6.5-9.0 x 5.0-7.0 µm, ovoid, lentiform, to submitriform in face-view, slightly narrower and inequilateral in profile, germ pore central, hilar appendage inconspicuous; spores dark-brown in deposit.
Solitary, scattered, or in small groups on thatch of grasses; also reported on Carex spp. (sedges), Typha spp. (cattails); fruiting during the summer months; locally common but inconspicuous.
Unknown, too small to have culinary value.
Coprinopsis friesii, is a small, grass-inhabiting mushroom recognized in youth by an obtuse-conic, striate, often radially torn cap. Remnants of a universal veil in the form of pallid flat scales decorate the cap, which in age becomes upturned and slightly deliquescent. Size and an ephemeral fruiting habit explain why this sometimes common mushroom is seldom collected. Fruiting bodies develop at night, shriveling away soon after dawn. Coprinopsis friesii should be compared with Parasola plicatilis and Parasola leiocephala. This species pair differs from Coprinopsis friesii in having larger, non-ornamented, convex caps with intact margins and spores that are heart-shaped to pentagonal in face-view. Other small grass-loving species that occur with Coprinopsis friesii include Panaeolus foenisecii and Agrocybe pediades. The former is a larger, brownish, convex-capped, non-deliquescent mushroom with a decurved, non-revolute margin, while Agrocybe pediades is a small, cream to tan-brown mushroom, the cap convex to plane, and like Panaeolus foenisecii, does not deliquesce.
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