The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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Hyphae of the trama weakly ochraceous-brown in KOH becoming paler on
standing. Clamp connections present.
Type locality. Near Centennial, Wyoming.
Habit and habitat. Cespitose on and by an aspen stub.
Distribution. Known only from type locality.
Observations. This species connects to P. obtusata and P. fulvescens but has
larger spores than either and it also fruits in clusters.
Material examined. Wyoming: Smith 34861 (Type), 35204.
270. Psathyrella prunuliformis (Murrill) A. H. Smith, comb. nov.
Atylospora prunuliformis Murrill, Mycologia 14: 266. 1922.
Psathyra prunuliformis (Murrill) Murrill, Mycologia 14: 278. 1922.
Illust. Text figs. 576, 577.
Pileus about 1 cm broad, obtuse to convex, surface glabrous, dry, rugose, pale
fawn color of light tan, margin concolorous, substriate. Context thin, pale tawny,
taste mild.
Lamellae adnate, broad, subdistant, subventricose, white.
Stipe about 5 cm long and 1 mm thick, equal, very slender, glabrous, concolorous, paler and brownish at the apex, hollow, whitish mycelioid at the base.
(Notes on the type): The structure of the pileus indicates clearly that the
species is very hygrophanous, and hence the above description (the original)
should be regarded as applying to faded basidiocarps. The material sectioned was
semisterile. This accounts for the pale gills as described.
Spores 10-12.5 x 5.6-7 u, smooth, apex truncate from a broad apical pore, shape
in face view ovate to elliptic, in profile somewhat inequilateral to obscurely so, as
revived in KOH the mature spores chocolate-brown.
Basidia 4-spored, 18-20 x 8.5-10 t, hyaline in KOH. Pleurocystidia and cheilocystidia similar and abundant, fusoid-ventricose with obtuse to rounded apex,
26-40 x9-15 /u, wall thin, smooth and hyaline, cell content not distinctive.
Caulocystidia not studied.
Gill trama regular, hyaline to yellowish in KOH (not distinctive). Pileus
trama brownish, the cuticle of vesiculose cells one cell deep, wall hyaline or
ochraceous to tan only at base, content not distinctive.
Type locality. New York Botanical Garden, New York.
Habit and habitat. In sandy soil in mixed wood, gregarious to clustered.
Distribution. New York (type examined).
Observations. The spores are more inequilateral in profile view than usual for
this genus and it is on this feature mainly that the species has been recognized.
Because of the partial sterility it is doubtful in this case as to whether the type
represents a normally reproducing population.
271. Psathyrella laeta A. H. Smith, sp. nov.
Pileus 2-4 cm latus late campanulatus vel convexus, glaber, fusco-cinnamomeobrunneus, nitens; lamellae angustae confertae sordide cinnamomeae demum fuscobrunneae dein fusco-vinaceo-brunneae; stipes 4-6 cm longus, 3-5 mm crassus,
albidus sursum pruinosus; velum nullum; sporae 9-12 x5-6 j; pleurocystidia
34-48 x 12-17 p, fusoideo-ventricosa, obtusa vel rotundata; fibulae adsunt. Typus.
Smith 43177 (MICH); legit prope Mackinaw City, Michigan.
Pileus 2-4 cm broad, obtusely conic expanding to broadly campanulate or