The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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rusty brown spores than usual as revived in KOH. Psathyrella avellaneifolia
has more distinctly thickened cystidial walls and the cystidia become much more
colored in KOH. When they can be compared on the basis of fresh material no
doubt other differences will come to light.
Material examined. Idaho: Smith 47260. Michigan: Smith 36179, 41325,
41538. Washington: Smith 14272 (Type).
118. Psathyrella rubicola A. H. Smith, Mycologia 42: 127. 1950.
Illust. 1. c., figs. 520-a, b, c, d, e.
Pileus 2.5-4 cm broad, convex to ovoid, becoming obtusely conic to convex or
finally plane, surface at first covered with white fibrils which soon are grouped
into fascicles and disappear (over the disc first), margin conspicuously fibrilloseappendiculate from remains of thick fibrillose patches of veil material, surface
"tawny-olive" beneath the veil, eventually tinged drab from ripening of spores,
the margin translucent striate in age before fading, hygrophanous and fading to
near cinnamon-buff or paler. Context watery, very fragile, odor and taste not
distinctive.
Lamellae pallid becoming grayish brown or darker, close, broad, broadly
adnate, readily seceding, edges even.
Stipe 4-5 cm long, 3-5 mm at apex, enlarged slightly downward, hollow and
fragile, white at first because of the dense fibrillose covering, usually with a
superior fibrillose zone, watery-pallid to grayish beneath the fibrils.
Spores 7.5-9x4-4.5 a, smooth, apex truncate from an apical pore which in
KOH often becomes "bubble-like," shape in face view elliptic to ovate, in profile
mostly obscurely inequilateral, color in KOH chocolate-brown, in Melzer's tawnyred, wall about 0.3 [, thick.
Basidia 4-spored, 20-28x8-10 Iu, clavate, hyaline in KOH. Pleurocystidia
abundant 46-60(-70) x 9-16 a, fusoid to fusoid-ventricose with acute apex and
very slightly thickened refractive walls (revived in KOH), hyaline to faintly
vinaceous revived in KOH, the walls often flexuous, with mucilaginous material
adhering near the tip in many but dissolving in KOH; no additional distinctive features seen in mounts in Melzer's. Cheilocystidia of two types: clavate
to vesiculose and up to 12-15 pt broad, these thin-walled and hyaline or yellowish
only at the base; or fusoid-ventricose with acute apex, 28-44x9-15 a, thinwalled, smooth, hyaline in KOH. Caulocystidia scattered and clavate, of various
sizes, thin-walled.
Gill trama pale cinnamon but soon fading to hyaline in KOH mounts. Pileus
with a cuticle in the form of a layer of vesiculose cells several deep, the cells very
large (50 /i wide or more), thin-walled, hyaline, smooth, and content not distinctive. Hyphae of the trama in the subcuticular region bright rusty brown in
KOH but fading in a few minutes, walls thin, smooth and hyaline to weakly
ochraceous (after standing in KOH). Clamp connections present. No distinctive
reactions noted for any tissue in mounts made in Melzer's.
Type locality. Lower Tahoma Creek, Mt. Rainier National Park, Washington.
Habit and habitat. Solitary or in small groups of 2-3 on canes of Rubus and
on rotten alder, July.
Distribution. Michigan, Washington.
Observations. The habitat on canes of Rubus is not an unusual feature when
one considers the amount of this debris which is available in the wet areas of the
Pacific Northwest.