Pileus up to 35 x 20 mm when still closed, up to c. 50 mm when expanded, first ellipsoid, cylindric-ellipsoid, pale to very dark grey-brown at centre beneath the whitish to silvery grey veil, paler towards margin, expanding to conical, then to convex or applanate, finally plano-concave with revolute margin. Veil first whitish, then silvery grey or pale grey to grey-brown, covering entire pileus, splitting up into hairy fibrillose, often pointed and appressed or - especially at centre - recurved flocks, the tips becoming brown on drying. Lamellae, L = c. 60, l = 3-7, free, narrow, rather crowded, first white, soon greyish brown to blackish. Stipe 50-100 x 2-5 mm, whitish, somewhat tapering towards apex, up to 8 mm wide at clavate to bulbous base, hollow, hairy flocculose, more dense at lower part, becoming glabrous with age.
  Spores [360,18,16] 9.8-14.2 x 6.2-8.3 µm; Q = 1.40-1.95, av. Q = 1.55-1.80; av. L = 11.3-12.9, av. B = 6.8-7.8 µm, ellipsoid or ovoid, with rounded base and apex, dark red-brown, and central, c. 1.6-2.0 µm wide germ pore. Basidia 16-42 x 8-12 µm, 4-spored, surrounded by 3-6 pseudoparaphyses. Pleurocystidia 70-150 x 20-60 µm, ellipsoid to oblong, utriform or subcylindric. Cheilocystidia 50-100 x 18-40 µm, ellipsoid to oblong or subutriform. Pileipellis a cutis, made up of cylindrical, sausage-like or fusiform elements, up to 150 µm long and 4-35 µm wide. Veil made up of elongate, sausage-like elements, 40-140(-180) x 10-40 µm, often inflated, usually constricted at septa; terminal elements ellipsoid, ovoid or fusiform. Clamp-connections present.

Habitat & distribution

  Common. Growing solitary or fasciculate on wood-chips, compost-heaps or vegetable refuse; one record (J. Daams 184) on large burned place. Wide-spread all over the world.

Remarks

  Coprinus lagopus can be recognized by the terrestrial habitat, preferably to wood-chips or vegetable refuse, the dense, hairy fibrillose, whitish to silvery grey veil, the average spore length > 11 µm and average spore breadth > 6.7 µm, and the thin-walled veil with terminal elements up to c. 40 µm wide.
  Close to Coprinus lagopus and exclusively growing in lawns, an aberrant form has been collected, characterized by very fragile basidiocarps that develop during the evening and night and quickly disappear the next morning, leaving only laying, silvery white stipes with collapsed caps and having somewhat larger (12-15 µm long) and very dark spores (coll. Uljé 1264 and 1268). Also a form is known from greenhouses with larger spores (14-16 µm long), but different from C. macrocephalus that has spores of the same length but distinctly broader. For the time being we refrain from describing these taxa awaiting more material.