The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Habit and habitat. On wet soil and organic debris, scattered.
Distribution. Michigan and Washington.
Observations. This agaric features a longer stipe than either P. fibrillosa or
P. gossypina. Further studies on it are desirable since Moser (1967) gives the
spores as 12-15 x 6.5-8 p.
Material examined. Michigan: Smith 34087, 34121. Washington: Imshaug
1961; Smith 30391, 30399.
177. Psathyrella squamosa (Karsten) Moser in Gams, Kleine Kryptogamenfl.
Ed. 2, IIb, 237. 1955.
Psathyra pennata var. squamosa Karsten, Symb. Mycol. Fenn. 6: 19(33). 1879.
Psathyra squamosa (Karst.) Karsten, Hedwigia 32: 59. 1893.
Pileus 10-20 mm broad, obtuse with an appressed margin becoming convex
to broadly convex, surface at first covered by white fibrils, or fascicles of fibrils
from the superficial outer veil, the margin at first appendiculate-fringed, soon
entirely glabrous, moist and hygrophanous, pale honey-color fading to pallid buff,
in age becoming more or less avellaneous toward the margin, the disc retaining a
tawny tinge. Context thin and fragile, odor and taste not recorded.
Lamellae moderately close, two tiers of lamellulae, narrow, broadly adnate,
pale brown when young, dull yellowish brown in age or clouded from the spores
(near "Dresden brown" to "mummy brown" as dried), edges white fimbriate.
Stipe 2.5-4 cm long, 1.5-2.5 mm thick, equal, fragile, white or whitish, tinged
yellowish when dry, lower portion more or less white-fibrillose from the remains
of the veil, pruinose above.
Spores 7.5-10 x 4.5-5 /A, smooth, apical pore distinct and apex slightly truncate,
shape in face view elliptic to ovate, in profile subelliptic to obscurely inequilateral,
color in KOH near "mummy-brown," somewhat grayer on standing, in Melzer's
tawny, wall about 0.3 ft thick.
Basidia 18-22 x 7-9,/, 4-spored, hyaline in KOH, clavate. Pleurocystidia very
abundant, 50-70x8-18,/, fusoid-ventricose, the apex acute to subacute and on
some with granules adhering around the apex, wall thin to slightly thickened and
distinctly refractive, cell content not distinctive in KOH or in Melzer's. Cheilocystidia 28-36 (-40) x 9-15 u, broadly fusoid-ventricose with acute apex or varying to clavate or saccate, the latter 12-18 x 7-12,, hyaline in KOH. Caulocystidia
mostly as clavate cells which collapse and do not revive well.
Gill trama hyaline in KOH, the hyphae somewhat interwoven. Pileus trama
hyaline to pale yellowish in KOH, no incrusting pigment noted. Cuticle of the
pileus of vesiculose cells, the layer several deep and the cells hyaline, thin-walled
and the cell content not distinctive. Clamp connections present. No distinctive
reactions noted for any tissue mounted in Melzer's.
Type locality. Finland.
Habit and habitat. On humus and debris.
Distribution. United States: Michigan, Oregon and Tennessee. Canada:
Ontario.
Observations. The short stipe and large pleurocystidia are distinctive in this
group.
Material examined. UNITED STATES. Michigan: Smith 21001, 21004,
25443, 25989. Oregon: Smith 28415. Tennessee: Hesler 15892; Smith 9839.
CANADA. Ontario: Smith 26501.