The North American species of Psathyrella.

296

MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

with white mycelium at the base, when crushed staining slowly to dingy vinaceousbrown, naked.
Spores 12-16 x 6-7.5 A, fuscous-brown in deposit, smooth, germ pore eccentric
to subapical and apex not truly truncate, shape in face view elliptic to subovate,
in profile subelliptic to obscurely bean-shaped (or ventral line straight), color
in KOH chocolate becoming dark chocolate, in Melzer's dark bay-brown, wall
about 0.4 A thick.
Basidia 4-spored, short-clavate, 18-22x7-9 A, hyaline. Brachybasidioles
present in mature hymenium. Pleurocystidia 38-57 x 12-18 A, fusoid-ventricose
with short neck and very obtuse to rounded apex, varying to nearly utriform,
smooth, thin-walled or wall about 0.4 A thick in some, hyaline in KOH, content
not distinctive in KOH or Melzer's. Cheilocystidia similar to the pleurocystidia
or varying to clavate.
Pileus cuticle a layer of vesiculose cells about 1 deep, walls thin, smooth
and hyaline, hyphae of subcuticular region hyaline in KOH and with smooth
walls. Clamps present.
Type locality. Ann Arbor, Michigan.
Habit and habitat. Gregarious on a lawn near shrubs and an old elm stump,
June.
Distribution. Known only from the type locality.
Observations. This species was at first mistaken for Psathyrella foenisecii
but the spores are smooth and pleurocystidia are present. Both species may
fade to whitish over the pileus. As dried, the pilei in the type collection are
coarsely striate but this was not evident on fresh material.
263. Psathyrella umbonata (Peck) A. H. Smith, comb. nov.
Psathyra umbonata Peck, Ann. Rep. N. Y. State Mus. 50: 106. 1897.
Atylospora umbonata (Pk.) Murrill, Mycologia 14: 267.1922.
Pileus 2-5 cm broad, campanulate, umbonate, margin straight when young
and with vestiges of a grayish fibrillose veil, purplish brown and striatulate when
moist, grayish white when dry, even or slightly rugulose, atomate, the umbo
commonly paler than the marginal area. Context submembranous, fragile.
Lamellae rather broad, moderately close, ventricose, subadnate, brownish red,
becoming purplish brown and finally almost black.
Stipe 5-10 cm long, 2-3 mm thick, slender, flexuous, hollow, white, commonly
hairy-tomentose at the base and slightly mealy at the top.
Spores 12-15 x6.5-8 /, smooth, somewhat truncate from an apical hyaline
pore, shape in face view elliptic to slightly angular-elliptic or ovate, in profile
subelliptic to obscurely inequilateral, color in KOH soon chocolate-brown, in
Melzer's more or less bay-red, wall about 1 pt thick.
Basidia 18-24 x 12-14 A, 4-spored, hyaline in KOH. Pleurocystidia scattered,
40-60 x 10-16 a, utriform, hyaline, thin-walled, smooth, cell content not distinctive
in KOH or in Melzer's. Cheilocystidia abundant, similar to the pleurocystidia
in shape but often smaller, Caulocystidia not studied.
Gill trama not reviving. Pileus trama poorly revived; cuticle of pileus of
vesiculose cells, no setae present.
Type locality. Lake Pleasant, New York.
Habit and habitat. Gregarious on chip-dirt.
Distribution. California, New York.
Observations. This is a relatively large Psathyrella for this subsection and