The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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var. kauffmanii
Illust. P1. 17; Text Figs. 96-100.
Pileus about (3-)4-8(-9) cm broad, campanulate becoming plane, surface
glabrous and moist, hygrophanous and slightly wrinkled when faded, honey
brown ("buckthorn brown") when young and becoming near "wood brown" as
spores mature (dark grayish brown), when faded grayish to alutaceous to dingy
pallid, scarcely translucent striate when moist, margin often appendiculate from
remains of the veil. Context fragile, moderately thick, concolorous with surface,
fragile, odor slight and not distinctive; taste mild to slightly bitterish.
Lamellae adnate, soon seceding, sometimes decurrent by a tooth, rather
narrow, close to crowded, whitish becoming gray and finally dusky drab, edges
white-fimbriate.
Stipe 6-12 cm long, (2.5-)3-10 mm thick at apex, 5-12 mm at base, white,
stuffed becoming hollow, pruinose at apex, glabrous elsewhere or slightly to
distinctly fibrillose-floccose below the annulus; annulus distant but not median,
membranous, persistent or evanescent, striate on upper surface, fragile.
Spores 7-9x 4.5-5 1, smooth, apical pore broad but very inconspicuous under
an oil immersion lens (apex rounded), shape in face view broadly oblong to
elliptic, in profile subelliptic to obscurely bean-shaped, color as seen in KOH dark
chocolate-color, in Melzer's reddish tawny, wall 0.3 t thick.
Basidia 4-spored, 10-26 x 8-11 I, clavate, hyaline in KOH. Pleurocystidia
abundant (34-)40-60 10-18 A, fusoid-ventricose to utriform, not infrequently
with 1-3 protuberances at or near apex or apex forked, mostly the apex obtuse
to broadly rounded, wall thin, smooth and hyaline in KOH, at times with
some amorphous debris adhering variously, content not distinctive in either KOH
or in Melzer's. Cheilocystidia vesiculose to clavate or fusoid-ventricose, 18-30x
8-16 g, the fusoid-ventricose cells with subacute to broadly rounded apex. Caulocystidia scattered to rare and merely vesiculose to clavate and 9-18 / broad,
hyaline, thin-walled, smooth.
Pileus with a cellular cuticle 1-3 cells deep, the wall thin, smooth and
hyaline in KOH, content not distinctive. Hyphae of the trama including subcuticular region hyaline to weakly tawny brownish (on young pilei), walls thin
and smooth. Clamp connections present. No distinctive reactions noted for
any tissue as revived in Melzer's.
Type locality. Big Bay, Michigan.
Habit and habitat. Gregarious to scattered under beech-maple stands with
some oak present.
Distribution. Michigan, New Mexico, Ohio, Virginia, Wyoming.
Observations. The distinguishing features of this species are the abundant
pleurocystidia with variable apex as described, habit on humus, relatively large
size, lack of reddish tinges to the gills (even as dried) and the dark colored spores
in KOH. In the latter features it is very similar to Drosophila leucotephra sensu
Kiihner & Romagnesi, but has abundant pleurocystidia.
Material examined. Michigan: Ammirati 1493, 1532; Kauffman 10-17-14;
Lange 902; La Rue 10-26-69; Potter 8838, 8865; Smith 20608, 20905, 21005, 21098,
21243, 32226, 32227, 32307, 33907, 35876, 36315, 36873, 38959, 41256, 41257, 41529,
41654, 44065, 49749, 57128, 57152, 62445, 63447, 66602 (Type), 66697, 71729,
75236, 75357, 75448, 77177, 77509; Thiers 2774. New Mexico: Barrows 549,
1008. Ohio: Walters 2, 184, 5-24-47. Virginia: Singer 481. Wyoming: Solheim
3350.