The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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obscurely inequilateral but mostly subelliptic and with the germ pore oblique,
wall about 1 [ thick.
Basidia 4-spored, 20-28(-33) x 10-12 t, elongate-clavate, hyaline in KOH or
tinged cinnamon on young specimens when first revived in KOH. Brachybasidioles
not differentiated. Pleurocystidia lacking or a few close to the gill edge and
resembling the cheilocystidia. Cheilocystidia abundant 36-50x10-16,u, fusoidventricose, apex obtuse to rounded, hyaline in KOH, wall thin, smooth and
hyaline, content not distinctive in either KOH or Melzer's. Caulocystidia rare
and approximately similar to the cheilocystidia. Hyphae of the stipe cortex with
weakly ochraceous pigmentation at septa and at times on the clamp.
Gill trama dark cinnamon in KOH fading to ochraceous-tawny or nearly
hyaline finally. Pileus trama dark rusty brown fading to ochraceous-tawny and
with hyphae roughened with pigment incrustations. Cuticle of pileus a palisade
of clavate to pear-shaped cells as in Conocybe, the pedicels often with ochraceoustawny slightly thickened wall extending to the flaring portion in which the wall
is thin, ochraceous to hyaline and smooth. Setae 80-250x4-7 t, with thickened
walls tawny in KOH, numerous in the cuticle and arising from the context. Clamps
present.
Type locality. Pole Mountain near Laramie, Wyoming.
Habit and habitat. Densely cespitose to subcespitose on soil and hummocks in
the vicinity of Populus tremuloides, spring and early summer.
Distribution. Wyoming.
Observations. This variant has slightly compressed spores and dull cinnamon
gills when young. It may eventually be found desirable to recognize it as a distinct
species.
Material examined. Wyoming: Smith 34727, 34729, 34731, 34732, 35326
(Type), 35327.
235. Psathyrella arenulina (Peck) A. H. Smith, comb. nov.
Agaricus arenulinus Peck, Rep. N. Y. State Mus. 30: 42. 1878.
Psilocybe arenulina (Pk.) Saccardo, Sylloge Fung. 5: 1057. 1887.
Illust. Text Figs. 532-534.
Pileus 1-3 cm broad, convex, becoming plane or centrally depressed, rarely
umbonate, in age sometimes with the margin uneven or wavy and widely and
irregularly striate, surface glabrous, hygrophanous, dark brown and slowly becoming wood brown as spores mature, fading to pale buff or practically white. Context
thin, rigid, very fragile, concolorous with pileus in moist or faded condition, odor
and taste not distinctive.
Lamellae close, adnate, cinnamon-brown becoming dark purplish brown, edges
even, not pink in age.
Stipe 3-5 cm long, 1.5-3.5 mm thick, hollow, slightly tapered upward, often
radicating and the underground portion enlarged from adhering sand, whitish
above ground, no veil seen.
Spores 9-12(-12.5) x5-6 [k, smooth, apical pore distinct and spore apex
truncate (but not broadly), shape in face view elliptic to somewhat wedge-shaped
(more broadly truncate at base than at apex) or ovate, in profile subelliptic to
obscurely bean-shaped, color in KOH cocoa-color slowly becoming darker, in
Melzer's reddish tawny, wall about 0.3 pu thick.
Basidia 4-spored, 20-30x9-12 /, clavate, hyaline, projecting 13 to / their
length when sporulating. Pleurocystidia none. Cheilocystidia abundant, 20-32 x