Macroscopic features

  Pileus 10 x 4 mm when still closed, up to 15 mm when expanded, ellipsoid conical oblong or ovoid, first white, soon more greyish. Veil white, often somewhat yellow-brown at centre, breaking up in patches. Lamellae free, rather crowded, first white, then greyish, finally blackish. Stipe up to 20 x 1-2 mm, whitish, base clavate, with small, tomentose disk.

Microscopic features

  Spores [40,2,1] 4.5-6.7 x 4.5-6.1 x 4.3-5.8 µm, the shape of a maize-kernel, truncate, medium red-brown, with central, c. 1 µm wide germ pore; Q = 0.95-1.25, av. Q = c. 1.10; av. L = 5.6-5.9, av. B = 5.2-5.4 µm. Basidia 14-26 x 8-9 µm, 4-spored, surrounded by 4-6 pseudoparaphyses. Pleuro- and cheilocystidia not found in type-material (see note). Elements of veil thin-walled, diverticulate, 2-7(-10) µm wide, slightly incrusted. Clamp-connections present.

Habitat & distribution

  Solitary or a few together. In grassland on calcareous soil. Very rare, only known from England.

Remarks

  Coprinus argenteus can be recognized by the typical shape of the spores in combination with the thin-walled velar elements. The type-material consisted of a fragment of a pileus only, and therefore no cystidia could be studied. In the original description no cystidia were mentioned and Orton stated: 'Cystidia not noted'.