The North American species of Psathyrella.

1972]

PSATHYRELLA

283

distinctly striate when moist. Context thin, exceedingly fragile, concolorous with
surface either moist or faded, odor not distinctive.
Lamellae very narrow and very crowded, ascending adnate, pallid brownish
gradually becoming cocoa-brown and when dried about the color of the pileus,
edges even.
Stipe 3-6 cm long, 2-4 mm thick, equal, fragile, hollow, pruinose above, naked
downward, white to pallid and not appreciably discoloring.
Spore deposit (on the stipe) cocoa-brown. Spores 6-7 x 4-4.5 /u, smooth, lacking a distinct apical pore, shape in face view fairly broadly elliptic, in profile
subelliptic to very obscurely inequilateral, color in KOH buffy hyaline, slowly
developing a faint avellaneous tinge, in Melzer's merely weakly ochraceous, wall
-0.2 / thick (rather thin).
Basidia 4-spored, 23-28x 7-9 /i, narrowly clavate, hyaline. Pleurocystidia
none. Cheilocystidia clavate, elliptic or ovate-pedicellate or utriform, 26-38x
10-16 /, hyaline, thin-walled, smooth, content not distinctive in Melzer's or KOH.
Caulocystidia similar to the cheilocystidia but measuring up to twice as large
at times.
Gill trama on young hymenophore bright orange-red in the region near the
subhymenium (in Melzer's) but this color not evident in age; the same color
pervading the pileus trama in immature basidiocarps. Pileus cuticle a staggered
layer 1-2 cells deep of inflated cells; the hyphae immediately beneath this layer
colored cinnamon to rusty ochraceous but pigment fading rapidly after mounting
in KOH. Clamps present.
Type locality. Ann Arbor, Michigan.
Habit and habitat. Cespitose-gregarious around hardwood stumps.
Distribution. Michigan.
Observations. This species is clearly closely related to P. hymenocephala but
is distinct by the absence of a veil. There are also numerous other minor features
which make it evident that the collections do not represent a single-character
variant of P. hymenocephala. Psathyrella varicosa Pearson (1950) is closely
related but is paler ("milky coffee") colored, the pileus is radiately veined, the
gills have eroded edges, the stipe is 6-12 cm long, and it was found in the Cape
region of South Africa. It grows in troops on the ground. The Michigan species
is named for the collector, Mrs. Florence Hoseney of the Michigan Botanical Club.
Material examined: Michigan: Hoseney 73, 76; Smith 72930, 72941.
244. Psathyrella albipes (Murrill) A. H. Smith, comb. nov.
Atylospora albipes Murrill, Mycologia 10: 22.1918.
Psathyra albipes (Murrill) Murrill, Mycologia 10: 33. 1918.
Pileus convex, about 1 cm broad, not umbonate, surface striate, finely asperulate, pale avellaneous, isabelline on the disc, margin straight, entire concolorous.
Context very thin and fragile.
Lamellae adnate, rather broad, crowded, white to pinkish, at length discolored.
Stipe 2-3 cm long, 1-2 mm thick, very slender, subcartilaginous, equal, white,
shining, hollow.
Spores 6-6.5 x4-4.2 /t, smooth, with an obscure hyaline pore and spore apex
not truncate, shape in face view ovate to elliptic, subelliptic to obscurely
inequilateral in profile, color in KOH a pale grayish brown.
Hymenium not reviving well enough to study. Cheilocystidia clavate to saccate, 24-32 x 9-12,u, thin-walled, hyaline, apparently smooth (reviving poorly).