The North American species of Psathyrella.

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on the disc, becoming grayish ("avellaneous" to "cinnamon-drab") as the spores
mature, opaque and whitish when faded unless dusted purplish brown from the
spores. Context moderately thick, whitish to pale pinkish buff, cartilaginous and
not particularly fragile, odor and taste not distinctive.
Lamellae crowded, narrow, squarely adnate, white, becoming "Rood's brown"
(dark vinaceous-brown) at maturity, edges even but in age minutely fimbriate.
Stipe 3-5 cm long, 3-5 mm thick at apex, slightly enlarged downward, white
or whitish, longitudinally striate below, pruinose-scabrous above, base with
cottony mycelium, no sign of a veil on smallest buttons.
Spores 7-8.5 (-9) x 3.5-4.5 g, smooth, apical pore present but small and apex
not distinctly truncated, shape in face view oblong to elliptic or slightly ovate,
in profile suboblong to obscurely inequilateral or some obscurely bean-shaped,
color in KOH cocoa-color becoming dark chocolate-color, in Melzer's tawny, wall
about 0.3 ut thick.
Basidia 4-spored, 18-27X 6-9 g, clavate, hyaline in KOH. Pleurocystidia
scattered, 36-62 x (8-)10-15 i, fusoid-ventricose, the apex obtuse and when
revived in KOH capped with amorphous to somewhat crystalline material, wall
thin and hyaline, content not distinctive in either KOH or in Melzer's. Cheilocystidia 32-50 x 9-18 g, fusoid-ventricose, apex usually incrusted, some with one
or more irregular protuberances. Caulocystidia varying from subcylindric to
subvesiculose, mostly broadly to narrowly clavate and 30-60 x 10-18 i, thinwalled, content not distinctive, surface mostly smooth or very slightly incrusted.
Type locality. France.
Habit and habitat. Densely cespitose around dead hardwood trees and stumps
or on chip dirt.
Distribution. United States: Michigan, New York, Oregon, Washington.
Canada: Ontario.
Observations. This name is here used tentatively since in Europe it is usually
referred to P. cernua as a synonym. Fries however described its gills as subventricose and white becoming cinereous and added "fusco-nigricantibus." In
our material in North America they are white and become dark vinaceous brown
(with a strong reddish tinge). See appendix II for an additional variant.
The group of species P. crenulata, P. cernua, P. polycephala, P. submaculata
and P. saccarinophila represent a typical stirps or collective species. Once the
group is circumscribed it will be interesting to see how many more variants can
be discovered by way of ascertaining patterns of developing diversity such as
those featuring P. crenulata and P. submaculata. A study of this group in culture
would be most appropriate.
Material examined. UNITED STATES. Michigan: Potter 8984; N. J. Smith
(Weber) 1772; A. H. Smith 984, 5044, 6044, 14951, 15290, 15339, 18790, 20668,
21095 21273, 33886. Oregon: Smith 20105. Washington: Smith 17345, 17878.
New York: Mrs. Hartnell, Oct. 10, 1943. CANADA. Ontario: DAOM 11743,
and Sept. 25, 1942; Kelly 1318. EUROPE. Austria: Lohwag 63.
212. Psathyrella cernua (Fries) Moser in Gams, Kleine Kryptogamenfl. II, 209.
1953.
Pileus 2-4 cm broad, convex with the margin connivent with the stipe, expanding to nearly plane in age, margin smooth, strongly hygrophanous, when moist
light to dark brown, becoming grayish and sometimes tinged pinkish fading to
pallid ochraceous, glabrous, veil remnants lacking on button stages, margin