The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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margin occasionally splitting, glabrous, or with pallid fibrils from partial veil
remnants along the margin in button stages, colors typically tawny ("ochraceoustawny") on disc and paler toward the margin, disc in some buttons near
"cinnamon-brown," when moist distinctly translucent-striate, fading to near
avellaneous (grayish) or pale dingy cinnamon-buff but soon with a pervading
pinkish hue. Context exceedingly fragile and thin, odor not distinctive.
Lamellae pallid ("tilleul buff") or slightly darker when young, purple-brown
(near "benzo brown") in age, broad, nearly subdistant when expanded, ascendingadnate and readily seceding, edges slightly flocculose and in age at times tinged
pinkish.
Stipe (3-4)5-10 cm long, 1-1.5 mm thick at apex, very slightly enlarged downward, pale honey-color or darker when young, in age pallid at apex, base paler in
some but mostly remaining honey-color, when young sparingly appressed floccose
from remains of the veil, glabrescent. Veil thin pallid and evanescent.
Spores 11-14x6-7.5 Kt (or up to 16x8.5 4), smooth, apical pore broad and
apex truncate, shape in face view elliptic to slightly ovate, in profile obscurely
to somewhat inequilateral, color in KOH date brown, darker on standing (finally
blackish brown), in Melzer's reddish tawny, wall 1-1.2 p1 thick in KOH.
Basidia 20-35 x 10-14 g, 4-spored or mixed 4- and 2-spored, clavate, hyaline.
Pleurocystidia scattered, 38-65 x 10-16 gk, ventricose-elongate with a short neck
and obtuse apex to fusoid-ventricose with long neck and subacute apex, smooth,
thin-walled, hyaline, cell content not distinctive in KOH or Melzer's. Cheilocystidia of two types: the first similar to the pleurocystidia having short necks,
the second vesiculose to clavate and 15-26 x 8-12 a, usually yellowish as revived
in KOH, the color located in the wall (some fusoid-ventricose cells also yellowish
at base). Caulocystidia mostly as hyphal ends cylindric to clavate and scattered
over apical region along with cells more or less resembling the fusoid-ventricose
cheilocystidia.
Gill trama nearly hyaline in KOH or if brownish soon fading. Pileus trama
of hyphae with cinnamon-brown to ochraceous-tawny walls having distinct pigment thickenings and incrustations (especially near cross walls), gradually paler
on standing. Cuticle of pileus an irregular palisade consisting mostly of clavatepedicellate cells with hyaline to hollow walls and tawny pedicels. Clamp connections present. No distinctive reaction seen on any tissue in mounts in Melzer's.
Type locality. Brutus, Emmet County, Michigan.
Habit and habitat. Scattered to gregarious on sticks and black muck in springy
areas such as along the edges of elm-ash swamps.
Distribution. Michigan.
Observations. This species is closely related to P. gracilis but is distinct in
having a slight veil, more heavily incrusted subcuticular hyphae in the pileus
trama, and in the hyphae of the stipe also showing incrustations near the cross
walls. As one would expect, the color of the fresh pileus also is much darker in
young basidiocarps.
Material examined. Michigan: Smith 25644 (Type), 25645, 25646, 25647,
25649, 25650, 25652, 25656, 25657, 25658, 25703, 25762, 26016, 26175, 26176, 26177,
28746,28748,28751,28753, 32248,32363,34120.
295. Psathyrella opacipes A. H. Smith, sp. nov.
Pileus 1-3.5 cm latus, convexus vel subplanus; glaber, rufo-fulvus demum
spadiceus, ad marginem demum vinaceus; lamellae adnatae latae, demum sub