The North American species of Psathyrella.

1972]

PSATHYRELLA

107

like the cheilocystidia but up to 100x 12 a, subcylindric, narrowly clavate or at
base slightly ventricose with a long flexuous neck above it ending in a subacute
apex, wall hyaline, smooth and thin. Cortex hyphae with "colloidal" content.
Pileus with a cuticle of a layer of vesiculose cells irregularly two to three
cells deep, their walls pale cinnamon-brown in KOH, smooth, thin, in Melzer's
merely ochraceous. Hyphae of the context weakly yellowish to hyaline in KOH
and yellowish in Melzer's, smooth. Clamp connections present. No distinctive
color reactions on any tissue when mounted in Melzer's.
Type locality. Indian Gap, (Great Smoky Mountains National Park),
Tennessee.
Habit and habitat. Cespitose on spruce logs.
Distribution. Tennessee. Type studied.
Observations. The hyphae of the stipe which show colloidal content in KOH
are merely yellow in Melzer's, not red as so frequently happens in other fungi
showing similar cell content. The spores have a granular content which in
Melzer's in some spores gives the impression of a minutely punctate condition,
but the wall itself, which is fairly thick, showed no sign of any discontinuity.
This species has the colored cuticular cells in KOH somewhat like that of P.
tsugae, but the spores separate the two at once. The caulocystidia appear to be
accentuated cheilocystidia but are distinctive nevertheless. Spores with a similar
pronounced apiculus are found in P. caputmedusae and its closely related
variants. The spore apex is rounded and under ordinary low power oil immersion
a distinct pore is not clearly visible.
65. Psathyrella cuspidata A. H. Smith, Contr. Univ. Mich. Herb. 5: 32. 1941.
Illust. 1. c. pl. 29, fig. 10; pl. 30, fig. 2. Text Figs. 167-169.
Pileus 1.5-3 cm broad across the base, up to 4.5 cm high, prominently conic
to cuspidate, becoming narrowly conic-campanulate or remaining conic, the
margin appressed against the stipe when young, flaring somewhat in age, covered
by a dense appressed coating of white fibrils at first, glabrescent around the disc
first but finally over all, margin usually remaining appendiculate with white
patches of fibrils, surface moist, "pinkish buff" when very young, becoming
"ochraceous-tawny" (pale rusty brown) as the pileus enlarges, the marginal
area changing to "light drab" to "drab" (livid gray) as the spores mature, the
umbo becoming "chamois" (pale yellowish), hygrophanous, fading to "tilleul
buff" (pallid) or slightly darker over all except the umbo which remains yellowish.
Context very rigid and very brittle, thin, concolorous with the surface, odor none,
taste mild.
Lamellae close to crowded or in age appearing subdistant, 20-25 reach the
stipe, narrow (about 2.5 mm), equal, ascending adnate, whitish when young
(paler than "tilleul buff"), "russet" to "Mars brown" (dark rusty brown) when
mature, edges even.
Stipe 4-8 cm long, 4-8 mm thick, equal or slightly narrowed toward the
apex, hollow, very fragile, when young coated with a thin layer of snow-white
fibrils, glabrescent and whitish below, surface often transversely undulate, in age
white fibrillose-scurfy above.
Spores 9-12 x 5-6.5 /x, smooth, apex truncate from a broad apical pore, shape
in face view mostly ovate with the apiculate end somewhat pointed, in profile
mostly somewhat inequilateral, color russet in water mounts when fresh, bister
in KOH and darkening somewhat but lacking a distinct violaceous component,
in Melzer's tawny but slowly becoming tawny-red, wall about 0.5 pt thick.
Basidia 4-spored, hyaline in KOH, 20-30 X 8-10 u, clavate. Pleurocystidia
scattered to abundant, 60-80 x 12-25 /,, broadly fusoid-ventricose, the neck short