Pileus 3-8 x 2-6 mm when still closed, up to 15 mm when expanded, conical, ovoid or ellipsoid, whitish with ochre centre. Veil breaking up in cream coloured to ochre patches. Lamellae, L = c. 40, l = 0-3, rather crowded, free, first white, then grey to blackish. Stipe up to 35 x 1-1.5 mm, white, greyish white, somewhat floccose at the slightly clavate base.
  Spores [180,9,9] 6.2-9.5(-10.8) x 5.5-7.2(-8.3) µm, ovoid to slightly rhomboid, mainly rounded at apex, medium red-brown, with central, 1.3-1.6 µm wide germ pore; Q = 1.10-1.40(-1.50), av. Q = 1.20-1.30; av. L = 7.6-8.3(-9.7), av. B = 6.0-6.8(-7.9) µm. Basidia 14-32 x 8-9 µm, 4-spored, surrounded by 5-7 pseudoparaphyses. Pleurocystidia 80-125 x 16-22 µm, (sub)cylindrical, oblong or narrowly conical. Cheilocystidia 30-100 x 14-32 µm, (sub)cylindrical, oblong, narrowly conical or ellipsoid. Elements of veil thick-walled, strongly multiple-branched and diverticulate, 2-8 µm thick; walls more than 1.5 µm thick, up to (2-)2.5-3(-4) µm in places and not or only slightly coloured. Clamp-connections present.

Habitat & distribution

  In small groups, a few together, generally on grasses. Common in Europe. Recorded from Canada, South America, North Africa.

Remarks

  Coprinus friesii can be recognized by the ovoid or rhomboid spores with average length of c. 8 µm in combination with the strongly thick-walled, not or slightly coloured veil. The type of Coprinus rhombisporus agrees in all characters with C. friesii and in is therefore considered synonymous. Coprinus friesii differs from the closest related C. pseudofriesii by smaller basidiocarps, not or only slightly coloured walls of veil which are more than 2 µm thick in places and the habitat: Coprinus friesii grows on grasses whereas C. pseudofriesii is mainly lignicolous.