The North American species of Psathyrella.

1972]

PSATHYRELLA

299

buff or retaining a grayish tinge, when water-soaked pale watery brown, faintly
fibrillose, becoming radially rugulose, margin not appendiculate. Context moderately thick on disc, thin on margin, pallid when faded, odor and taste not
distinctive.
Lamellae adnate to decurrent by a line, close, moderately broad, pale gray
becoming "hair brown" (dark brownish gray), as dried dark vinaceous-brown,
edges fimbriate and pallid.
Stipe 5-9 cm long, 2.5-6 mm thick, equal, fragile-cartilaginous, glabrous, apex
white-pruinose, longitudinally striate, white and unchanging, often sharply curved
at the base and matted-mycelioid. Veil white, arachnoid and all traces soon
vanishing.
Spores "fuscous" in deposits, 8-11 x 5-6.5 A, smooth, apical pore indistinct and
apex not truncate, shape in face view ovate to elliptic, in profile somewhat
inequilateral to obscurely bean-shaped, color in KOH immediately clay color to
dull ochraceous-tawny, slowly becoming nearly hyaline, in Melzer's tawny, wall
about 0.4 / thick in Melzer's and 0.6-0.7 M in KOH.
Basidia 4-spored, 20-24 x 6-8 t, narrowly clavate. Pleurocystidia rare to
scattered, 40-62 x 10-20 A, broadly fusoid-ventricose with obtuse to rounded apex,
utriform, or pedicellate-elliptic to subfusiform, readily collapsing, wall thin,
smooth and hyaline, content not distinctive. Cheilocystidia (30-)40-60x10-25
(-30) pu, broadly utriform, broadly fusoid-ventricose with rounded apex, or
clavate-pedicellate to pedicellate-subfusoid (large and conspicuous), all types
thin-walled, smooth and hyaline in KOH.
Hyphae of gill trama with greatly inflated cells with smooth hyaline walls,
subhymenium narrow and indistinct. Pileus cuticle a layer of vesiculose cells
2-4 deep, their walls smooth, hyaline or nearly so. Hyphae of the subcutis hyaline
or nearly so in KOH and the walls smooth. Clamp connections present.
Type locality. Great Smoky Mountains National Park, Tennessee.
Habit and habitat. Scattered on rich humus in mixed forest.
Distribution. Known only from type locality.
Observations. This species is most closely related to P. subagraria but is
distinguished by the very slight development of the veil, the color of the spores
in KOH, by the often extremely broad cheilocystidia, and to some degree by the
narrower stipe although there is significant overlap in this last feature.
267. Psathyrella baileyi A. H. Smith, sp. nov.
Pileus 2-3.5 cm latus, convexus, glaber, cinnamomeo-brunneae, demum sulcato
striatus; lamellae confertae, latae, atro-brunneae; stipes 5-10 cm longus,
2-3.5 mm crassus, glaber, ad basem albo-myceliosus, sursum pruinosus; velum
nullum; sporae 9-12 x5-6,u; pleurocystidia 40-55 x6-14 /, utriformia; fibulae
adsunt. Typus. Bailey 125 (MICH); legit Isle Royal National Park, Michigan.
Illust. Text Figs. 567, 568.
Pileus 2-3.5 cm broad, obtuse to convex, becoming broadly convex, surface
glabrous, moist, translucent striate on the margin, in age slightly sulcate, dark
cinnamon-brown to a redder brown when moist, fading to pale dingy tan or more
or less avellaneous (grayish). No veil remnants present. Context very thin and
fragile, brownish; odor and taste not recorded.
Lamellae close but not crowded, bluntly adnate, moderately broad, blackish
at maturity but edges whitish to pallid (not pink).
Stipe 5-10 cm long, 2-3.5 mm thick, equal, white mycelioid at the base,