The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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when fresh a medium honey brown (close to "buckthorn brown"), becoming
grayer as spores mature, when faded pale avellaneous over marginal area and
a dingy tan over the disc (very ordinary coloration for the genus). Context thin
and membranous, fragile, odor and taste not distinctive.
Lamellae close, adnate-seceding, broad, brownish when young, becoming
dark chocolate-color by maturity and when dried blackish, edges even.
Stipe 4-6 cm long, 3-5 mm thick, equal, fragile, whitish becoming merely
pallid above, discoloring over basal area to dingy brownish, glabrous or nearly
so, with a median to superior membranous annulus which is striate on the upper
surface.
Spores 8-10x 5-6.2 u, smooth, apical pore distinct, shape in face view ovate
to elliptic, in profile view subelliptic to obscurely inequilateral, color in KOH at
first the color of a roasted coffee bean but slowly darkening to dark chocolatecolor (with more of a violaceous tone), in Melzer's dark bay-brown (not as
red as in most species), wall about 0.5-0.7 u thick.
Basidia 4-spored, 24-30x 8-11 M (near the base of the gill, shorter near the
edge), clavate, hyaline in KOH. Pleurocystidia scattered, 26-45 x 10-18 t broadly
and obtusely fusoid to broadly fusoid-ventricose with scarcely any neck and
apex broadly rounded to obtuse, wall thin, smooth and hyaline, content not
distinctive. Cheilocystidia vesiculose to broadly fusoid-ventricose and then resembling the pleurocystidia, hyaline to yellowish in KOH, 18-30x9-15 A or
merely 10-15 K wide if vesiculose. Caulocystidia none located other than an
occasional clavate to vesiculose hyphal end-cell.
Pileus with a cuticle of hyaline cells 2-3 deep with their long axes arranged
vertically and when crushed out many found to be broadly pyriform, walls thin,
smooth and hyaline, content not distinctive in either KOH or Melzer's. Hyphae
of the cocoa-colored subcuticular region (in KOH) showing some wall thickenings
near the septa, the color fading on standing, hyphal walls smooth or nearly so
over most of their area. Clamp connections present. No distinctive reaction
noted for any tissue when revived in Melzer's other than an orange tint to the
subhymenium which fades in a few minutes.
Type locality. Pole Mountain, near Laramie, Wyoming.
Habit and habitat. On moist soil under aspen, especially around beaver dams.
Distribution. Idaho, Montana, Utah, Wyoming.
Observations. This species is close to P. kauffmanii but the latter differs in
having longer pleurocystidia which tend to produce bulges and projections at or
near the apex in mature or old specimens, in not having a coating of floccose
fibrils over the stipe below the annulus, and in slightly larger spores with thicker
walls.
Material examined. Idaho: Cooke 18569. Montana: McKnight F7863.
Utah: McKnight F77. Wyoming: Smith 34576, 34579, 34597, 34660, 34725,
34726, 34728, 34737, 34740, 34763, 34764, 34774, 34899, 34902, 34905, 34924, 34925,
35109, 35209; Solheim 2178 (Type), 2855, 2856, 2857, 2859, 2860, 2864, 3345.
31a. Psathyrella solheimii var. sanjuanensis A. H. Smith, var. nov.
In exsiccata annulus gossypinus avellaneus; sporae 8-10.5x4.5-6/; pleurocystidia 38-50 x 10-13 x 8-10 /, ad apicerum rotundata vel subcapitata. Typus.
Smith 51837 (MICH); legit Ophir, Colorado.
Pileus 1-3.5 cm broad, convex, expanding to broadly convex, surface glabrous,
moist and hygrophanous, tawny to near "buckthorn brown," fading to pale