The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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Basidia 20-26 x 6-9 u, 4-spored, narrowly clavate, hyaline in KOH. Pleurocystidia abundant, fusoid to fusoid-ventricose, 36-54 x 10-15 u/, wall smooth, apex
acute, content usually very pale to distinctly vinaceous-gray to vinaceous brownish, homogeneous, in Melzer's not distinctive, wall in the neck often flexuous and
also in many refractive and up to 0.4 pA thick. Cheilocystidia in part similar to
pleurocystidia and in part clavate to vesiculose, typically hyaline as revived in
KOH. Caulocystidia more or less like the pleurocystidia but not colored in KOH
and walls not refractive, rather rare.
Gill trama regular, vinaceous-brown in KOH in young pilei (as revived),
nearly hyaline in old ones. Pileus having a cuticle of a layer of vesiculose cells
1-2 deep, most with yellowish walls revived in KOH, cell content not distinctive.
Hyphae of the trama vinaceous-brown in KOH but fading, walls smooth to
minutely roughened. No distinctive reactions observed in mounts made in Melzer's
for any tissue.
Type locality. University of Michigan Biological Station, Cheboygan County,
Michigan.
Habit and habitat. Subcespitose to gregarious on rotting hardwood logs, June.
Distribution. Michigan, Oregon.
Observations. The important features of this species are the smooth pleurocystidia many of which show some color on standing in KOH, the small spores
typically ovate in face view, and the avellaneous gills when young.
The European P. spintrigeroides is close to this species but has slightly larger
spores and yellowish pleurocystidia in KOH.
Material examined. Michigan: Bartelli 2243; Potter 8826; Smith 20762, 21463
(Type), 21511, 22318, 23394, 36252, 41380, 41534, 57112, 64704, 74418, 74420,
78271. Oregon: Smith 24241, 24242, 24414.
75a. Psathyrella avellaneifolia var. perplexa A. H. Smith, var. nov.
Pileus (1.5-)2-4 cm latus, convexus fibrilloso-squamulosus glabrescens, ad
marginem appendiculatus; fulvus; lamellae angustae confertae vinaceo-brunneae;
stipes 3-5 cm longus, 2-3 mm crassus, fragilis, albidus albo-fibrillosus, glabrescens;
sporae 6-7 (-8) x 3.5-4 ju; pleurocystidia 40-67 x 9-13 (-17) /, fusoidea, acuta vel
obtusa in "KOH" hyalina vel pallide avellanea; fibulae adsunt. Typus. Smith
32479 (MICH); legit prope Douglas Lake, Michigan.
Illust. Text Figs. 191,192.
Pileus (15-) 20-40 mm broad, convex, surface decorated with patches of fibrils
from the copious universal veil, margin decorated with rather copious veil fragments, surface moist, rich tawny, fading to tan but darkening in drying. Context
thin, fragile, concolorous with surface in either moist or faded condition, odorless.
Lamellae narrow, close, cocoa-colored after being dried, edges whitish.
Stipe 3-5 cm long, 2-3 mm thick, equal, fragile, whitish, at first whitefibrillose from remains of the outer veil, glabrescent.
Spores 6-7(-8) x3.5-4 a, smooth, apical pore present but obscure, apex not
truncate (but in KOH a "bubble" often forming on the spore apex), shape in face
view narrowly wedge-shaped to suboblong, in profile obscurely inequilateral to
obscurely bean-shaped, color in KOH pale tawny when first mounted, soon cocoacolor and finally chocolate-brown, in Melzer's ochraceous-tawny, wall about
0.2 K or less thick.
Basidia 4-spored, 16-20x7-8 JL, clavate, hyaline in KOH. Pleurocystidia
abundant, 40-67x9-13(-17) a, fusoid to fusoid-ventricose, apex acute to sub