The North American species of Psathyrella.

1972]

PSATHYRELLA

139

"cinnamon-brown" or "sepia," hygrophanous and fading to "clay color" or
"cinnnamon-buff," often glistening when faded, usually fading first around the
disc. Context concolorous with the surface, thickish under the disc, thin toward
the margin, fragile, odor and taste mild.
Lamellae bluntly adnate and soon seceding, moderately broad (about 3 mm),
close, 29-33 reach the stipe, "tilleul buff" when very young, becoming sordid
brownish and finally "light drab" at maturity, edges even.
Stipe 4-8 cm long, 3-7 mm thick, equal, hollow, fragile, glabrous, white, often
transversely undulate but not flexuous, apex sometimes faintly pruinose.
Spores (7-) 8-10 x 4.5-5.5 x 5-6.5 a, smooth, compressed slightly, apex with
a distinct hyaline pore, shape in face view strongly ovate to somewhat ovate, in
profile subelliptic varying to obscurely inequilateral or to obscurely bean-shaped,
color in KOH blackish brown (about "mummy brown"), in Melzer's dark baybrown, wall about 0.6 / thick.
Basidia 4-spored, abruptly clavate, 14-17x 7-9 u, hyaline in KOH. Pleurocystidia scattered, 36-54 x 10-16 A, utriform to fusoid-ventricose with thick neck
and broadly rounded to very obtuse apex, hyaline, smooth, thin-walled. Cheilocystidia saccate to broadly ventricose with short slightly constricted necks and
very obtuse apex, hyaline, thin-walled, content not distinctive. Caulocystidia
similar to pleurocystidia but more variable in size, some small to large clavate
cells also present.
Pileus with a cuticle of vesiculose cells 2-3 deep, their walls smooth, hyaline
and thin, content not distinctive. Hyphae of the trama cinnamon-brown to
vinaceous-brown in KOH, walls not obviously incrusted. No distinctive color
changes on any tissue as revived in Melzer's. Clamp connections present.
Type locality. Finland.
Habit and habitat. Gregarious to scattered on debris of alder and cottonwood.
Distribution. California, Oregon, Washington.
Observations. The type variety is regarded here as a Psathyrella with only a
thin fibrillose veil and as such is just as logically placed in the P. spadiceogrisea
group. Var. velosa however, has a heavier veil appendiculate on the pileus margin
at first.
Material examined. California: Smith 56936. Oregon: Gruber 7-7; Kauffman 10-6-22; Smith 19237, 19686, 19900, 23854, 24285, 24339, 24567, 24643,
24740, 27335, 28054, 28055, 55744, 55745. Washington: J. B. Flett 2-26-41;
Imshaug 1867; Simmons 1437, 1744, 1745; Smith 13184, 13242, 13255, 13608,
14119,14209,14505,14625, 29783,29820,29826, 30085, 30503, 30607.
93a. Psathyrella subnuda var. velosa A. H. Smith, var. nov.
Pileus ad marginem appendiculatus; velum albidum, submembranaceum.
Typus. Smith 73947 (MICH); legit prope Priest Lake, Idaho.
Illust. Text Figs. 232-235.
Pileus 2.5-4 cm broad, obtusely conic, expanding to broadly conic, margin
straight at first, glabrous except for a few thin patches of fibrils along the
margin and the edge appendiculate with fragments of a white veil, soon entirely
glabrescent, dark cinnamon-brown to dull clay color and margin striate, hygrophanous and fading on disc first to dingy tan (near "cinnamon-buff"). Context
very thin and fragile, odor and taste not distinctive, with FeSO, no color change.
Lamellae close, moderately broad, ascending-adnate, seceding, brownish, when