Summary:
Psathyrella epimyces is characterized by a silky cap, fruiting on Coprinus comatus fruitbodies, and relatively thick-walled spores lacking a readily observable germ pore.

Cap:
2-6cm across, ovoid to spherical when young, becoming broadly convex to nearly flat, the margin sometimes elevated when old; not hygrophanous, white but becoming sordid when old; silky-fibrillose, margin fibrillose-appendiculate when veil breaks, (Smith), up to 5cm across, first rounded then extended; whitish, silky, later dirty white; fringed margin from partial veil remnants, (Schalkwijk-Barendsen)

Flesh:
thick, soft; white or whitish, (Smith), white, (Schalkwijk-Barendsen)

Gills:
narrowly adnate or at times somewhat adnexed, narrow, broadest toward the cap margin, thin; pallid at first, soon blackish brown and when dried blackish, edges white; edges fimbriate [fringed], (Smith), adnate; pale gray at first, then blackish brown with light edges, (Schalkwijk-Barendsen)

Stem:
2-7cm x 0.5-1.5cm, equal or widening downward, fleshy, "stuffed solid but becoming hollow, soft, floccose-mealy, striate", white-annulate [with white ring] near base or not, "or veil remnants appearing volva-like", (Smith), up to 6cm long and up to 1.5cm wide, hollow; white; woolly, (Schalkwijk-Barendsen)

Veil:
white, leaving an evanescent ring near the base of the stem that resembles a volva, (Schalkwijk-Barendsen)

Odor:
not distinctive (Smith)

Taste:
not distinctive (Smith)

Microscopic spores:
spores 7-9(10) x 4-5 microns, in face view ovate to elliptic, in side view subelliptic to very obscurely inequilateral, smooth, germ pore not distinct, in KOH dark chocolate-color, in Melzer''s reagent bay-brown, wall 0.7-1.0 microns thick; basidia 4-spored, 24-34(48) x 7-9 microns, "clavate, pedicel often long and flexuous", colorless in KOH, merely yellowish in Melzer''s reagent; pleurocystidia 40-64(70) x 9-15 microns, "broadly fusoid-ventricose with obtuse apex varying to subcylindric with rounded apex, pedicel often distinctly elongated", wall thin, smooth, and colorless as revived in KOH, cell content not distinctive in either KOH or Melzer''s reagent, cheilocystidia "similar to but smaller than the pleurocystidia and more of them with an obtuse to subacute apex"; clamp connections present, (Smith)

Spore deposit:
blackish (Smith, Schalkwijk-Barendsen)

Notes:
It has been reported at least from BC (collections at University of British Columbia), WA (a collection at the University of Washington), AB and YT, (Schalkwijk-Barendsen), and ON, MI, MN, NY, and WI, (Smith(5)).

EDIBILITY

Synonyms and Alternate Names:
Stropharia epimyces (Peck) G.F. Atk.