The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Lamellae close, narrow, ascending-adnate, two tiers of lamellulae, dull brownish becoming dark grayish brown ("hair brown") and blackish brown as dried,
edges whitish.
Stipe long and flexuous, 9-10.5 cm long, 3-3.5 mm thick at apex, up to 4.5-5 mm
near the base, hollow and very fragile, readily splitting lengthwise, surface white,
apex pruinose, base slightly fibrillose; veil lacking.
Spores 10-12.5 x4.5-6 /, smooth, apical pore distinct and apex of spore
truncate, shape in face view ovate varying (less commonly) to elliptic, in profile subovate to obscurely to somewhat inequilateral, color in KOH very dark
cocoa-brown at first, becoming a medium chocolate-brown, in Melzer's dark
reddish brown to tawny, wall about 0.3,/ thick.
Basidia 4-spored (16-)18-24 x8-12 I, subglobose above a short broad pedicel
or merely clavate (when sporulating). Brachybasidioles vesiculose. Pleurocystidia
scattered to abundant, 42-68x9-18 I, fusoid-ventricose with obtuse apex, some
pedicellate-elliptic in optical section and about 20 u broad, wall thin to slightly
thickened (-0.5 I) but highly refractive, hyaline, cell content not distinctive.
Cheilocystidia very abundant 32-44x 9-14 ~u, fusoid-ventricose, the apex obtuse,
smaller than the pleurocystidia, hyaline, thin-walled, content not distinctive.
Gill trama regular, the hyphae more or less parallel, pale chocolate-brown in
KOH at first but soon fading to dingy brown to dull pale yellow-brown, finally
nearly hyaline. Pileus trama of interwoven hyphae at first cocoa-colored in KOH
but gradually fading to dingy brown; walls smooth or practically so. Cuticle of
pileus of vesiculose cells one cell deep, the walls thin and hyaline in KOH. Clamps
present.
Type locality. Baker Lake, Washington.
Habit and habitat. On a meadow in a campground.
Distribution. Washington.
Observations. The pallid pileus, medium-large spores, highly refractive pleurocystidial walls and dark grayish brown gills at maturity are distinctive. It is close
to P. elwhaensis but differs in features of the veil and pleurocystidia.
282. Psathyrella roothaanensis A. H. Smith, sp. nov.
Pileus 1-3 cm latus, conicus vel convexus, ad marginem fibrillosus, glabrescens, cinnamomeus vel cinnamomeo-brunneus; lamellae cinnamomea demum fulvae vel fumoso-fulvae; subdistantes, latae; stipes 4-12 cm longus, 1.5-2.5 mm
crassus, fragilissimus, fibrillosus glabrescens, pallidus; sporae 8-11(-12) x 5-6 L;
pleurocystidia (34-)40-60x9-16 i, fusoide ventricosa, acuta; fibulae adsunt.
Typus. Smith 73753 (MICH); legit prope Upper Priest River, Idaho.
Illust. P1. 77, fig. b; Text Figs. 601-603.
Pileus 1-3 cm broad, obtusely conic to convex, expanding to broadly conic to
broadly convex, surface at first with more or less of a zone of white fibrils near
the margin and some fibrils over the disc, very soon glabrescent, hygrophanous,
dark cinnamon-brown on the disc, grayish cinnamon-brown over the striate
margin, striate becoming subsulcate as pileus fades. Context very thin and fragile,
odor and taste not distinctive.
Lamellae dull cinnamon-brown becoming pale russet, finally grayish chocolate
color, broadly adnate, seceding, subdistant to close, narrow to moderately broad,
edges even.
Stipe 4-12 cm long, 1.5-2.5 mm thick, equal, tubular, exceedingly fragile, pallid