The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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("wood brown") as spores mature, the disc dingy cinnamon in age ("Sayal
brown"), at first with white fibrillose squamules over the plicate portion. Context
thick but exceedingly fragile, odor strong and sweetly fragrant, taste very
disagreeable.
Lamellae close, broad (12 mm), depressed adnate, when mature cinnamondrab with some areas more rusty brown (obscurely mottled), edges even.
Stipe up to 15 cm long, 17 mm thick at apex, equal, hollow, rather fibrous,
with a median annulus having wood brown to vinaceous-brown fibrils on lower
side near the margin, below the annulus the stipe surface having appressed
brown fibrils variously distributed, surface above annulus scurfy whitish and
longitudinally striate from gill impressions.
Spores 9-12 x 4-4.5 x 4.5-5 A, smooth, apical pore not evident, apiculus prominent, shape in face view ovate-apiculate, in profile obscurely bean-shaped, varying
to obscurely inequilateral, as revived in KOH soon dark chocolate-color, in
Melzer's tawny red, wall about 0.3 g thick.
Basidia 24-30 x7-10 u, 4-spored. Pleurocystidia 36-54 x 10-16 /, broadly
fusoid-ventricose with obtuse to rounded apex, thin-walled, smooth, lacking
distinctive content in either KOH or Melzer's. Cheilocystidia subtibiiform to
ventricose-rostrate to fusoid-ventricose to subvesiculose, hyaline and thin-walled
or a few with yellowish slightly thickened walls (to 0.5 IA). Caulocystidia more
versiform than the cheilocystidia and more with yellowish walls in KOH, some
elongated to 120 p.
Pileus with a cellular cuticle 4-8 cells deep, walls weakly yellowish as revived
in KOH, smooth, content of cells not distinctive. Subcuticular layer yellowish
becoming nearly hyaline in KOH, walls smooth and thin. Clamp connections
present. No distinctive iodine reactions noted on any tissue or in any cells.
Type locality. Ashford, Washington.
Habit and habitat. Solitary near conifer stumps, October, rare.
Distribution. Known only from the type locality (Smith 49412).
Observations. The brown fibrils on the annulus and below it on the stipe
are not the result of mere discoloration of originally pallid fibrils, they are
brown in button stages. These colored fibrils in addition to the very disagreeable
taste distinguish this species from P. caputmedusae which has spores about the
same size. Both have the fragrant odor. Still another species closely related to
P. caputmedusae is P. jerdonii as redescribed by Orton (1960) from the type.
However, it apparently lacks pleurocystidia. The annulus, and apiculate spores
lacking a truncate apex place it here.
28. Psathyrella caputmedusae (Fries) Konrad & Maublanc, Encyc. Mycol. 14:
127. 1949.
Agaricus caput-medusae Fries, Epicr. Syst. Mycol. 216.1838.
Stropharia caputmedusae (Fr.) Karsten, Bidr. Finl. Nat. Folk, 493. 1879.
Hypholoma caputmedusae (Fr.) Ricken, Die Blatterpilze, 243. 1912.
Geophila caputmedusae (Fr.) Quelet, Enchir. Fung. 112. 1886.
Drosophila caputmedusae (Fr.) Kiihner & Romagnesi, Fl. Anal. 371. 1953.
Illust. Smith & Stuntz (1950). Figs. 18b, c, d, 19. P1. 16, fig. b; Text Figs. 82-85.
Pileus 4-5 cm broad at base, nearly 3 cm high, obtusely campanulate, surface
at first covered with small whitish superficial fibrillose scales which show a
tendency to become fuscous or bister at the tips, glabrescent, surface dark
"snuff brown" to pale "snuff brown" (a medium date brown) over the disc,
near sepia toward the margin, hygrophanous and fading to grayer in streaks