Summary:
Coprinopsis friesii is recognized by the ovoid or rhomboid spores with average length of about 8 microns in combination with the strongly thick-walled, not or slightly colored veil elements, (Ulje(1)). Other features are a white to whitish cap that is sometimes tinted brownish toward the center and that becomes pale gray, the cap surface finely scaly centrally and becoming vaguely striate; crowded, nearly free gills that deliquesce somewhat; a whitish stem with a flattened basal disc or the base at least slightly clavate; and fruiting typically on dead monocots. Coprinopsis friesii was in Subsection Alachuani.

Cap:
0.3-0.5cm high when unexpanded, narrowly paraboloid-conic, expanding to flat, with edges becoming revolute [upcurved]; "white to whitish, sometimes tinted faintly brownish towards the center", becoming pale mouse gray when fertile; "finely appressed floccose scaly towards the disc", when fertile becoming vaguely striate, (Redhead), 0.3-0.8cm x 0.2-0.6cm when still closed, up to 1.5cm when expanded, conic, ovoid or ellipsoid; whitish with ocher center; veil breaking up in cream to ocher patches, (Ulje), 0.4-0.8cm high, grayish white; striate, (Hansen, L.), 0.3-1.2cm across, leather-pallid whitish, when old margin often with violaceous tone; sulcate [grooved], when old almost bald, (Moser), gray to grayish purple with white veil scales, (Trudell)

Gills:
nearly free, ascending, crowded, somewhat deliquescing when old; white, becoming grayish sepia, (Redhead), free, rather crowded, about 40 reaching stem, 0-3 subgills between neighboring gills; at first white, then gray to blackish, (Ulje), with a purplish tinge (Hansen, L.), when old with violaceous tone, (Moser), gills liquefy only slightly if at all (Trudell)

Stem:
0.5-2cm x 0.02-0.05cm, subequal [nearly equal]; white; nearly bald to minutely pulverulent [powdery]; "with a flattened basal disc fringed with tapering radiating mycelial strands", (Redhead), up to 3.5cm x 0.1-0.15cm, base slightly clavate; white, grayish white; somewhat floccose at the base, (Ulje), 2-3cm x 0.1-0.15cm, pubescent, (Hansen, L.)

Odor:
indistinct (Buczacki)

Taste:
indistinct (Buczacki)

Microscopic spores:
spores 7.5-9.3 x 5.5-7.9 microns, "usually broadly ovate in face view", varying to broadly elliptic, inequilateral in side view "with a less convex surface on the abaxial surface", smooth, thick-walled, brown vinaceous in mass, sienna in water, with well-developed apical germ pore; basidia 4-spored, 15-21 x 8.8-9.7 microns, dimorphic, "subglobose with a short to long tapering pedicel, spaced by swollen brachybasidia forming a rosette pattern"; pleurocystidia scattered, numerous, 70-75 x 14-20 microns, subcylindric to fusoid, thin-walled, colorless, cheilocystidia "polymorphic, a mixture of shorter pleurocystidia-like elements, swollen brachybasidium-like elements and thin-walled veil-like elements forming a mat over the lamellae edges"; cap veil elements 2-4.5 microns wide, loosely interwoven, "somewhat duplex, lower elements with a poorly developed coralloid branching pattern, thin-walled, sometimes obscurely roughened", colorless or faintly brownish, tending to deliquesce early, "upper or outer elements normally well developed but sometimes nearly lacking, with a well developed thorny to antler-like branching pattern, thick-walled, having numerous elongated narrow branchlets which are solid or nearly so, smooth to vaguely roughened", "veil elements loosely attached to the trama tissue which lacks a well developed pellis", (Redhead), 6.2-9.5(10.8) x 5.5-7.2(8.3) microns, oval to slightly rhomboid, "mainly rounded at apex, medium red-brown", with central, 1.3-1.6 micron wide germ pore; basidia 4-spored, 14-32 x 8-9 microns, surrounded by 5-7 pseudoparaphyses; pleurocystidia 80-125 x 16-22 microns, (sub)cylindric, oblong or narrowly conic, cheilocystidia 30-100 x 14-32 microns, (sub)cylindric, oblong, narrowly conic or ellipsoid; elements of veil "thick-walled, strongly multiple-branched and diverticulate", 2-8 microns thick, walls more than 1.5 microns thick, up to (2)2.5-3(4) microns in places and not or only slightly colored; clamp connections present, (Ulje), spores 7.5-9 x 6.5-8.5 x 5-6 microns, subglobose [nearly round], flattened, (Hansen, L.), spores 8-10 x 7.5-9 x 5.5-7 microns, in face view almost round, (Moser), spores 7-11 x 6-7 x 7-9 microns, lentil-shaped, (Trudell)

Spore deposit:
dark brown (Buczacki)

Notes:
Coprinopsis friesii has been found in WA (S. Trudell, pers. comm., Trudell(4)). It has been reported from BC (O. Ceska, pers. comm.). It has been found in CA (Desjardin(6)). Collections were examined from ON, QC, United Kingdom, Sweden, and it has been reported also from Morocco and Japan, (Redhead). It is common in Europe, and recorded also from Canada, South America, and North Africa, (Ulje(1)).

EDIBILITY

Synonyms and Alternate Names:
Coprinus friesii Quel
Coprinus rhombisporus P.D. Orton