The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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cuticular cells the angles where cells meet thickened and tawny in KOH. Not
distinctive in any way when mounted in Melzer's. Clamps present.
Type locality. Ann Arbor, Michigan.
Habit and habitat. Solitary to cespitose around stumps of elm and ash,
June-July.
Distribution. Michigan, Minnesota, Ohio.
Observations. This is one of the largest and most fragile species in the genus
and has exceptionally large pleurocystidia. It is common here in southeastern
Michigan now that our elms are all dead and decaying, but has a short fruiting
period and so is rarely collected.
Material examined. Michigan: Baxter 6-26-20; Hoseney 1766; Kauffman
(Type); Smith 1327, 15124, 38949, 60779, 62155, 62315, 62441, 63442. Minnesota:
Weaver 1294. Ohio: Walters 6-9-46.
81. Psathyrella subagraria (Atkinson) A. H. Smith, comb. nov.
Psilocybe subagraria Atkinson, Ann. Mycol. 7: 375. 1909.
Illust. P1. 40, 41; Text Figs. 204-206.
Pileus (2-)3-7(-10) cm broad, obtuse to convex, the margin incurved somewhat, expanding to campanulate, umbonate or plane, at times the margin elevated in age but usually merely spreading, surface moist, hygrophanous to subhygrophanous and scarcely changing color when fading, surface covered by minute
innate whitish to grayish fibrils or appearing nearly glabrous, margin appendiculate with veil remnants, colors pale grayish (pale "drab") when young, at maturity
the disc somewhat darker and near avellaneous or "wood brown" the margin
gradually becoming pallid. Context rather thick, watery-punctate, white.
Lamellae narrow (5-6 mm), subdistant to close, widest at the stipe and tapering to the margin of the pileus, white to pallid grayish when young, becoming dull
purplish brown at maturity, edges even.
Stipe 6-12 cm long, (2.5-) 3-8 (-12) mm thick, hollow, equal or nearly so, base
clavate at times, fragile, pure white, surface covered by loose fibrils over lower
portion, glabrescent, pruinose and somewhat striate above, often obscurely
undulate.
Spore deposit purple-brown. Spores 8-10x4-5(10-12x4.5-5.5 p/)/u, smooth,
apical pore present but not prominent, shape in face view oblong to elliptic or
slightly ovate, in profile obscurely inequilateral to slightly bean-shaped, color
purple-brown in water mounts fresh, cocoa-brown in KOH as revived but
on standing becoming dingy ochraceous, in Melzer's near ochraceous-tawny, wall
about 0.3 f thick.
Basidia 2- and 4-spored, 22-28(-35) x9-12 a, hyaline in KOH. Pleurocystidia 36-60x 10-18 a/, scattered, usually broadly ventricose, above a narrow
pedicel and the neck scarcely constricted (utriform), apex broad and rounded,
hyaline and smooth, thin-walled, collapsing readily, content not distinctive.
Cheilocystidia 40-60 x 10-16 /, more or less similar to pleurocystidia, saccate to
vesiculose cells also present. Caulocystidia resembling the pleurocystidia but
varying to clavate to vesiculose (and up to 30 / broad if the latter shape), hyaline,
smooth, thin-walled, content not distinctive.
Pileus cuticle of vesiculose cells 2-3 thick, hyaline in KOH, walls thin and
smooth, content not distinctive; fibrils above the cuticle dingy ochraceous in KOH
and with some incrusting material present on some. Hyphae of the trama of
hyaline to weakly ochraceous hyphae as revived in KOH, the cells very broad.