The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

violaceous-gray, broad, nearly subdistant, adnate but soon seceding, edges even.
Stipe 4-6 cm long, 2.5-3 mm thick, equal, fragile, dingy honey-color below,
merely pallid above, thinly fibrillose over lower half, white pruinose above.
Spores 8-9(-10) x4.5-5 /k, smooth, apical pore distinct, shape in face view
elliptic to slightly ovate, in profile subelliptic to obscurely inequilateral, color in
KOH bister becoming date brown, in Melzer's reddish tawny, wall about 0.3 ju
thick.
Basidia 4-spored, very short, subelliptic to clavate, 15-20x8-11 tu, hyaline.
Brachybasidioles present in mature pilei, subglobose or with a slight pedicel.
Pleurocystidia 42-65x9-15 a,, fusoid-ventricose, thin-walled, hyaline, apex in
many as revived in KOH with granular material over or around it. Cheilocystidia
32-40 x 10-18 /A, broadly fusoid to clavate, hyaline in KOH, thin-walled, smooth
or with adhering debris. Caulocystidia clavate to fusoid-ventricose, of various
sizes, thin-walled, smooth, content not distinctive.
Pileus with a cuticle of vesiculose cells 1-2 deep, walls smooth, hyaline to pale
cinnamon, thin (as revived in KOH), content not distinctive. Hyphae of context
tawny to pale tawny in KOH and with some local wall thickenings but for the
most part smooth. No distinctive reaction on any tissue when revived in Melzer's
but some highly refractive hyphae present. Clamp connections present.
Type locality. Priest River, Idaho.
Habit and habitat. Gregarious on debris, October.
Distribution. Colorado and northern Idaho.
Observations. Psathyrella fulva has much the appearance of P. fulvescens
but with a heavier veil and grayer lamellae at maturity. Also, brachybasidioles
are present at maturity.
Material examined. Colorado: Smith 52877. Idaho: Smith 73799 (Type).
126. Psathyrella similis (Parker) A. H. Smith, Contr. Univ. Mich. Herb. 5:
58. 1941.
Hypholoma simile Parker, Mycologia 25: 195. 1933.
Illust. Parker, 1. c. pl. 26, fig. 6.
Smith, 1. c. pl. 28, figs. 6-9. Text Figs. 290-292.
Pileus 2-3.5 cm broad, ovoid in button stages, becoming obtusely conic to
campanulate, surface at first covered over all with scattered patches of buff
fibrils, the margin appendiculate with veil remnants, soon glabrescent, evenly
"russet" or darker when young, becoming paler and near "cinnamon-brown"
before fading, hygrophanous, fading to dark tan on the disc and sordid grayish
buff-brown toward the margin, sometimes nearly "cinnamon-buff" over all,
atomate. Context concolorous with the surface, very thin and fragile, odor and
taste mild.
Lamellae bluntly adnate, broadest (3-4 mm) at the attachment to the stipe
and tapered evenly toward the margin of the pileus, readily seceding, close, pallid
cinnamon-brown when young, soon dark fuscous-brown, edges whitish.
Stipe 4-5 cm long, 2-3 mm thick, equal, strict, fragile, hollow, white, base with
a rather copious white mycelium, lower part sparsely white fibrillose, toward the
apex densely floccose-pruinose.
Spores 8-10x5-6 pu [8.5-10.2(-13) P, Parker 1933], smooth, with an apical
hyaline germ pore, shape in face view approximately elliptic, in profile obscurely
bean-shaped to subelliptic, color in KOH soon chocolate-brown, in Melzer's bay
reddish, wall about 0.3 u thick.