E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include a powdery cap that is white with a flesh-colored tinge, free close gills that are white flushed pale pinkish, a powdery stem that is generally white but may be tinged pinkish or reddish toward the base (the color may be obscured by white surface cells), a white spore deposit, and small spores. "Cystolepiota seminuda is a complex - morphologically all very similar looking fruitbodies, differences in the ITS," (Else Vellinga as communicated to Buck McAdoo).

Cystolepiota seminuda occurs mainly east of the Great Plains but it also occurs in the Pacific Northwest and CA (Phillips). Miller(14) say it is apparently widely distributed and it is known by the authors from MT. Breitenbach(4) give the distribution as North America, Europe, Asia, and North Africa. There are collections from BC at the University of British Columbia. The University of Washington has collections from WA, CA, ON, and MI.

Cap:
1-3cm across, "conico-convex with a distinct umbo; white with a flesh-colored tinge"; mealy, (Phillips), 1-2.5(3)cm across, convex to nearly flat; "hydrangea pink", often whitish along margin; "covered with a dense powdery coating at first aggregated into fine warts but in age evenly distributed", becoming nearly bald and micaceous glistening when old; margin at first appendiculate, (Smith, H.V.), 1-2.5(3)cm across, convex to flat; disc pale pink, margin whitish with deciduous membrane hanging from edge; cap covered with deciduous powder, (Sieger)

Flesh:
thin; white in cap, pinkish in lower stem, (Phillips), thin but firm, tapered evenly to margin; white, (Smith, H.V.)

Gills:
"free, close; white flushed pale pinkish", (Phillips), approximate to stem, close, broad and ventricose, about 0.3cm broad, 1 tier of subgills; white, unchanging; edges even, (Smith, H.V.), free, close, wide in middle, in 1 tier; white or pale pink, unchanging; edges even, (Sieger)

Stem:
1.5-2.5cm x 0.1-0.2cm, "thin, fragile; white tinged pinkish toward the base; finely mealy", (Phillips), 2-4cm x 0.15-0.3(0.4)cm, equal in upper part and indistinctly bulbous at base, hollow; white in upper part, "hydrangea pink" or darker at base, the color often obscured by surface powder; at first covered by powder up to the evanescent [fleeting] ring zone, when old only faintly powdery or cottony, (Smith, H.V.), 2-4cm x 0.15-0.3(0.4)cm, equal in upper part and swollen at base; upper part white, lower part pale pink covered with deciduous powder that when old becomes glistening flakes, (Sieger)

Veil:
transient (Phillips), ring not persistent (Sieger)

Odor:
not distinctive (Smith, H.V., Sieger)

Taste:
in some faintly like Lepiota cristata, never strong, (Smith, H.V.), like grain (farinaceous) or not distinctive, (Sieger)

Microscopic spores:
spores 3-4 x 2-2.5 microns, elliptic, smooth, (Phillips), spores 4-5 x 2.5-3 microns, elliptic, pale brown in Melzer''s reagent; basidia 4-spored, 10-15 x 4-5 microns, clavate; pleurocystidia none, cheilocystidia none; gill trama compact, subparallel; cap cuticle of spherical thin-walled cells 20-30 microns in diameter, (Smith, H.V.), spores 4-5 x 2.5-3 microns, elliptic, without germ pore, pale brown or colorless in Melzer''s; pleurocystidia absent, cheilocystidia absent; cap cuticle globose cells with thin walls, (Sieger)

Spore deposit:
white (Phillips)