The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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Basidia 4-spored, 24-30 x 9-11 fu, clavate with the pedicel narrow, hyaline in
KOH; scattered basidioles containing a homogeneous pale tawny pigment as
revived in KOH. Pleurocystidia 40-80x9-17 L/, scattered to abundant, not
appreciably clustered, utriform to subcylindric, walls thin, smooth and hyaline,
content not distinctive in either KOH or Melzer's. Cheilocystidia causing the
edge to be sterile they are so numerous, 50-80 x 10-14 t/, filamentous-subcapitate to
narrowly utriform, smooth, hyaline, thin-walled. Caulocystidia scattered, clavate
to elongate-ventricose, 40-80 x 9-16 /, hyaline, thin-walled content not distinctive.
Gill trama regular, pale ochraceous-tawny as revived in KOH from color in
the smooth walls. Pileus with a cuticle 3-4 cells deep, the cells vesiculose and with
dull ochraceous to pale tawny walls in KOH, walls smooth; filaments projecting
from this layer 8-12 ju wide and at first with fine incrustations but these largely
disappearing in KOH, nearly hyaline on standing; subcuticular region with
hyphae having pale fulvous walls in KOH, no incrustations or wall thickenings
noted. Context hyphae merely paler than the subcuticular hyphae, lacking any
distinctive reaction in Melzer's. Clamp connections present.
Type locality. Heart O'Hills, Mt. Angeles, near Port Angeles, Washington.
Habit and habitat. Densely gregarious on waste ground, along roads and
sometimes in lawns, late spring and again in the fall, common in the Olympic
Peninsula of Washington.
Distribution. Michigan, Oregon, Washington in the United States and Quebec
in Canada.
Observations. This species differs from P. rigidipes in the cinnamon colored
context, smaller spores, and abundant pleurocystidia. P. pyrotricha has spores
10-12 x 5-7 /A according to Moser and other European authors.
Material examined. UNITED STATES. Idaho: Smith 54483, 76957. Michigan: Smith 16957 (Type), 64606, 67809, 78342. Oregon: Smith 19703, 19832,
19846, 24186. Washington: Smith 14154. CANADA. Quebec: Smith 61639.
Psathyrella subg. Psathyroides (Lange) A. H. Smith, stat. nov.
Hypholoma sect. Psathyroides Lange, Dansk Bot. Arkiv 4: 41. 1923.
Psathyrella sect. Psathyroides (Lange) Singer, Agar. Modern Taxon. 507. 1963.
Drosophila subg. Pluteopsis Kiihner & Romagnesi, Fl. Anal. 369. 1953.
In this group the spores are smooth though some may be angular, the
pleurocystidia are not clustered, and the pileus is fibrillose to such a degree that
the hygrophanous nature of the surface typically is at least somewhat obscured.
Typically the fibrils on the pileus are colored and innate, the pigment being
located in the wall in some and in others in the cell content. The fibrils arise
from among the cells of the cuticle.
In addition to the species keyed in the following treatment, certain others
may be sought for here because of their fibrillose pilei. These are 25. P. epimyces,
23. P. insignis, and 139. P. canoceps. The rule to follow in making an identification to subgenus is that if the fibrils are innate, try the key to Psathyroides
first.
This group is treated under the name Psathyroides in Kiihner & Romagnesi
(1953). The type of that subgenus is generally considered to be very close to
P. corrugis.
Type. Hypholoma melanthinum (Fr.) Karsten.
There are a number of concepts of this species extant, but all appear to apply
clearly to this group.