The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

ish (in KOH), content not distinctive in either KOH or Melzer's. Cheilocystidia
vesiculose, 9-15 t wide, thin-walled, hyaline. Caulocystidia not found.
Pileus cuticle a layer of vesiculose cells 1-2 cells deep, the walls hyaline to
yellowish in KOH, cell content not distinctive. Hyphae of the trama in the
subcuticular region hyaline to yellowish in KOH and the cells smooth. Clamps
present. When revived in Melzer's no distinctive reaction on any tissue noted.
Type locality. Wilderness State Park, Emmet County, Michigan.
Habit and habitat. Gregarious on debris in a clearing for a power line,
September.
Distribution. Michigan, Utah.
Observations. The distinguishing features of this species are the milk-white
pileus just before maturity, the long narrow pleurocystidia, short fat cheilocystidia, pale cocoa-colored spores which in KOH darken slowly and only slightly,
and the white to watery-grayish stipe.
Material examined. Michigan: Smith 43146 (Type). Utah: McKnight F947.
358. Psathyrella subsimilissima A. H. Smith, sp. nov.
Pileus 1-3 cm latus, late conicus, glaber, cinnamomeo-brunneus; contextu cum
"FeSO4" sordide olivaceus; lamellae pallidae demum fusco-brunneae, latae, confertae; stipes 2.5-3.5 cm longus, 1-2.5 (-3) mm crassus, deorsum melleibrunneus,
sursum albidus, sparse fibrillosus, glabrescens; velum pallide griseum, sparsum;
sporae 6.5-7.5 (-8) x 4-4.5 (-5) /, pleurocystidia 38-60 x 9-14 ), anguste fusoideoventricosa, obtusa; fibulae adsunt. Typus. Smith 66680 (MICH); legit prope
Burt Lake, Michigan.
Illust. P1. 89, fig. c; Text Figs. 802-804.
Pileus 1-3 cm broad, obtusely conic, expanding to broadly conic, surface
glabrous, moist and hygrophanous, margin fringed with grayish fibrils of the
rudimentary veil, all traces soon vanishing, colors cinnamon-brown on disc and
tawny to ochraceous-tawny on margin at maturity, if moist somewhat striate.
Context watery brown, odor and taste mild or slightly fungoid, with FeSO, slightly
olivaceous on the disc.
Lamellae pallid to avellaneous, becoming wood brown, broad, close, adnateseceding, edges whitish.
Stipe 2.5-3.5 cm long, 1-2.5(-3) mm thick, equal or slightly larger below,
surface white above from a thin fibrillose-floccose coating, glabrescent, basal area
discoloring to honey brown.
Spores 6.5-7.5(-8) x 4-4.5 (-5) I, smooth, apical pore inconspicuous, shape in
face view ovate to elliptic, in profile bean-shaped to obscurely inequilateral, color
in KOH cocoa-color slowly darkening somewhat, in Melzer's reddish tawny, wall
about 0.2 A thick.
Basidia 4-spored, 24-30x8-10,, clavate, hyaline in KOH. Pleurocystidia
abundant, 38-60x9-14 [, subfusoid to narrowly fusoid-ventricose, apex obtuse,
wall thin, smooth, hyaline, cell content not distinctive. Cheilocystidia clavate and
9-16 A wide or vesiculose, or fusoid to narrowly fusoid-ventricose as for the
pleurocystidia but smaller. Caulocystidia clavate to vesiculose or resembling
pleurocystidia, 10-20 u wide and of various lengths, hyaline, thin-walled, smooth.
Pileus cuticle 2-5 cells deep, the cells vesiculose to clavate and having walls
colored pale cinnamon in KOH (either on fresh or revived material), walls thin
and smooth. Subcuticular region cinnamon in KOH and the hyphal walls smooth