The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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hyaline. Pileus trama floccose and loosely interwoven, dull rusty brown in KOH
but with a tinge of cocoa-color. Cuticle formed of an irregular palisade of large
clavate cells mostly with very broad bases, hyaline or only faintly yellowish in
KOH. Clamp connections present.
Type locality. Near West Branch, Michigan.
Habit and habitat. Solitary on muck under aspen.
Distribution. Michigan.
Observations. In stature this species reminds one of P. gracilis but differs in
having much shorter and extremely rare pleurocystidia and in having a veil.
Material examined. Michigan: Potter 4834; Smith 18305 (Type), 26004.
313. Psathyrella tenera Peck, Rep. N. Y. State Mus. 47: 18. 1894.
Illust. Text Figs. 675,676.
Pileus 6-10 mm broad, obtuse to campanulate, surface moist and subhygrophanous reddish cinereous when moist, paler when dry, slightly rugulose
and atomate when faded. Context thin and very fragile.
Lamellae broad, adnate, plane or but slightly ascending, subdistant, at first
pallid or subcinereous, then umber and finally blackish, white on the edges.
Stipe 2.5-4 cm long, scarcely 1 mm thick, slender, glabrous, stuffed or hollow,
white, with a white floccose mycelium at the base.
Spores (11-)12-15(-16) x5.5-7 u/, smooth, apical pore distinct and apex
truncate under oil, shape in face view oblong to narrowly elliptic but more or
less pointed at the base, in profile subelliptic or with ventral line straighter than
the dorsal line in optical section, color in KOH black or nearly so, in Melzer's
bay-brown, wall 1.3 A thick.
Basidia 4-spored, clavate, hyaline, 20-30 x 9-12 u. Brachybasidioles present.
Pleurocystidia rare to scattered, 27-38 x 8-12 I,, fusoid to fusoid-ventricose, apex
obtuse to subacute, wall thin, smooth and hyaline (at first with some granular
material adhering but this soon disappearing in KOH or Melzer's), content not
distinctive. Cheilocystidia similar to the pleurocystidia, hyaline.
Gill trama hyaline in KOH, of irregularly arranged inflated cells. Cuticle of
pileus of vesiculose cells in a layer (1-)2-3 cells deep, hyaline in KOH and readily
collapsing. Hyphae of the context of enlarged cells which are compactly arranged,
hyaline in KOH or finally merely slightly discolored. Clamps present.
Type locality. Pierrepont Manor, Jefferson County, New York.
Habit and habitat. On damp mucky ground in open woods.
Distribution. Idaho, Michigan, New York, Ohio, Washington.
Observations. This is one of the small delicate species not very often recorded
probably because the basidiocarps are so ephemeral.
Material examined. Idaho: Smith 65853. Michigan: Smith 20275, 26253.
New York: Peck's type. Ohio: Cooke 33112. Washington: Smith 29601.
314. Psathyrella intermedia (Peck) A. H. Smith, comb. nov.
Panaeolus intermedius Peck, Bull. Torrey Club 22: 205. 1895.
Pileus 13-25 mm broad, campanulate or convex, even, glabrous, moist and
hygrophanous, grayish brown.
Lamellae ascending or subarcuate, subdistant, adnate, black when mature.
Stipe 5-10 cm long, 0.5-1.5 mm thick, slender, often elongated, hollow, grayish
brown, white-pruinose at the top.