The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

and some wall thickenings most numerous near the septa. No amyloid or fleeting
amyloid reaction present in any tissues, no distinctive coloration in Melzer's.
Clamps present.
Type locality. Owyhee County, Idaho.
Habit and habitat. Gregarious under sagebrush in June after heavy rains.
Distribution. Southwestern Idaho.
Observations. This is obviously a rare species since the conditions favoring
its fruiting in a semi-desert habitat may not be realized more than once in ten
years. The broadly ellipsoid spores which do not develop a violet-fuscous tone
until they have been in KOH a half hour or more are distinctive in the genus. The
encrusted hyphae of the subcuticular zone, the rusty brown gills and small
pleurocystidia are additional characters.
374. Psathyrella borealis A. H. Smith, sp. nov.
Pileus 1-3 cm latus, conicus vel convexus, subcastaneus, glaber; lamellae
violaceo-fuscae, confertae latae; stipes 4-6 cm longus, 1.5-2.5 mm crassus, pallidus, demum griseo-brunneus, sparse fibrillosus, glabrescens; sporae 8-10 x 4-5 ~;
pleurocystidia 42-64 x 9-15 tk, fusoide ventricosa, subacuta; fibulae adsunt. Typus.
Smith 43743 (MICH); legit prope Castle Rock, St. Ignace, Michigan.
Illust. Text Figs. 758-761.
Pileus 1-3 cm broad, obtusely conic at first, expanding to broadly conic or
convex, a rich cinnamon-brown when moist, fading on disc first to a dull tan or
ochraceous-tawny, margin naked or practically so at all times. Context thin, very
fragile, odor and taste not distinctive.
Lamellae near benzo brown at maturity (near fuscous), close, broad, adnate,
seceding, edges whitish.
Stipe 4-6 cm long, 1.5-2.5 mm thick, equal, fragile, tubular, whitish throughout at first but in age watery gray to watery brownish, at first with a very thin
coating of white fibrils from a poorly developed veil, soon glabrescent, apex
pruinose.
Spores 8-10x 4-5 /, smooth, apical pore distinct, shape in face view elliptic
to subovate, in profile subelliptic to obscurely inequilateral, color in KOH soon
dark chocolate-color, in Melzer's soon reddish tawny, wall about 0.3 u thick.
Basidia 4-spored, 20-24x7-8 A, hyaline in KOH. Pleurocystidia 42-64 X
9-15 pu, fusoid-ventricose, apex subacute, thin-walled, hyaline, smooth, content
not distinctive in KOH or Melzer's. Cheilocystidia similar to pleurocystidia but
shorter and an occasional vesiculose cell observed. Caulocystidia fusoid-ventricose
and resembling the cheilocystidia (including the presence of vesiculose-pedicellate
cells).
Cuticle of pileus a layer of vesiculose cells 1-3 deep and some cells up to 60,u
wide, the cells with hyaline, smooth walls and the cell content not distinctive.
The subcuticular region vinaceous-brown in KOH, with incrusted or locally thickened hyphal walls. Clamp connections present. None of the tissues when mounted
in Melzer's show a distinctive color reaction.
Type locality. St. Ignace, Michigan.
Habit and habitat. Gregarious in Sphagnum at edge of a bog.
Distribution. Idaho, Michigan.
Observations. This species features medium-sized spores, large fusoidventricose pleurocystidia with subacute apex, extremely large inflated cells in