Summary:
Features include 1) a conic to bell-shaped cap that is at first white to brown under a white universal veil layer which becomes fibrils and scales, the cap striate becoming deeply pleated, 2) fragile flesh, 3) free to adnexed gills that are pale then brownish and deliquescing with most or all of the cap, 4) a white stem often with veil remnants, 5) growth on wood or on the ground, and 6) microscopic characters. This species was in Section Lanatuli of Coprinus sensu lato. Coprinopsis cinerea is the more recently published name based on molecular evidence (Redhead(49)). C. cinerea belongs to the Coprinopsis lagopus group. This description, derived from Van De Bogart(2) except where indicated, is C. cinerea var. cinerea. Var. depressa (described from WA) differs in that spores have a conspicuous suprahilar depression, rather than the normal rounded wall. Features of var. cinerea include 1) an acorn-shaped to revolute, whitish to grayish to brownish cap with pleated-striate margin, 2) free, crowded gills that are pale then brown then black and deliquescent, 3) a white stem, 4) habitat on wood or seemingly terrestrial, and 5) deep brownish black to soot black spore deposit. Note that the online Species Fungorum, accessed March 22, 2014, lists among the synonyms of this taxon Coprinus fimetarius var. cinereus (L.) F., Coprinus fimetarius var. macrorhizus (Pers.) Sacc., and Coprinus macrorhizus (Pers.) Rea.

Cap:
1.5-3.5cm long when unexpanded, 2-6cm across after expansion, long glandiform [long acorn-shaped] at first, becoming conic, then bell-shaped and finally revolute [upturned] and laciniate; at first white to pale brown and darker brown at top under a white universal veil layer, becoming dark gray to gray-brown; smooth, bald, and lubricous when fresh under the veil, the veil becoming fibrils and scales, loose and easily lost; striate from the first and becoming deeply plicate-striate [pleated-striate]

Flesh:
thin and fragile in cap and stem

Gills:
free to adnexed, crowded at first then less so, narrowly lanceolate, sometimes with numerous subgills also present, 0.5-3.3cm x 0.1-0.6cm; pale then brownish and eventually soot black, autolysis eventually includes most or all of cap

Stem:
5-18cm x 0.17-0.7cm, hollow, slender, widening downward, often enlarged at base; white and opaque to slightly translucent in small specimens; sometimes smooth and bald, but often with strigose woolly fibrils at base

Veil:
universal veil present on cap and often on stem base as fibrils and scales

Microscopic spores:
spores 9-15 x 5.6-8.1 microns, elliptic, round in cross-section, smooth, germ pore apical, 1.5-2.7 microns in diameter, apiculus small but usually visible, no well-defined suprahilar flattening, "deep chestnut brown to deep purple-black or almost opaque in 3% KOH", contents sometimes guttulate; basidia 4-spored, trimorphic, short clavate and 17.5-22.0 x 8.0-11.2 microns, long clavate to subululiform and 26.0-31.2 x 8.5-11.2 microns, ululiform and 32.0-37.5 x 8.1-11.2 microns; pleurocystidia 108.0-192.5 x 40.0-95.0 microns, elliptic, often with short pedicel 2.0-4.0 microns in length, colorless, smooth, thin-walled, bridging between gills, cheilocystidia somewhat variable, some spherical, 18.7-65.0 microns in diameter, some broadly ovate or ellipsoid, 48.0-112.5 x 16.0-75.0 microns, colorless, smooth, thin-walled, tend to be fused into membrane uniting adjacent gills; no other cystidia present; clamp connections present on universal veil, on stem, in cap trama, and in gill trama

Spore deposit:
deep brownish black to soot black

Notes:
Coprinopsis cinerea has been found at least in WA (var. cinerea and var. depressa) and BC (var. cinerea) (both from Van De Bogart(2)). It has also been found elsewhere in North America. Breitenbach(4) give the distribution as Europe and Asia.

EDIBILITY

Synonyms and Alternate Names:
Coprinus cinereus (Schaeff.: Fr.) Gray