The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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92. Psathyrella olivaceopallida A. H. Smith, sp. nov.
Pileus 3-5 cm latus, conicus demum plano-umbonatus, glaber, lacteo-albus
demum ad centrum olivaceo-griseus, ad marginem denticulato-appendiculatus;
lamellae pallidae demum griseo-fuscae, adnatae angustae; stipes 5-9 cm longus,
3-5 mm crassus, albidus rare annulatus; sporae 7-9 x4-4.5 A; pleurocystidia
30-45x 9-18 tt; fibulae adsunt. Typus. Smith 4991 (MICH); legit prope Burt
Lake Cheboygan County, Michigan.
Illust. Text Figs. 229-231.
Pileus 3-5 cm broad, obtusely conic expanding to plano-umbonate, surface
glabrous, moist, hygrophanous, milky white to pale olive-buff when young, the
margin finally becoming watery grayish and the disc watery pinkish buff,
striatulate before fading; margin at first denticulate with flaps of the submembranous whitish veil. Context thin, pallid, fragile, odor and taste mild, FeSO,
no color change.
Lamellae whitish becoming nearly "hair brown" (a brownish gray), no red
or cinnamon tints evident, close, narrow, adnate, soon seceding, edges even.
Stipe 5-9 cm long, 3-5 mm at apex, equal, white, unchanging, naked or nearly
so, rarely with a thin annulus, drying pallid.
Spores 7-9x4-4.5 A, smooth, with a hyaline apical pore, shape in face view
oblong to narrowly elliptic, or narrowly ovate and slightly truncated at the base,
in profile obscurely bean-shaped to obscurely inequilateral, color in KOH dark
chocolate-color on standing, dark cocoa-color when first revived, in Melzer's dark
tawny-red, wall about 0.3,p thick.
Basidia 4-spored, clavate, hyaline in KOH. Pleurocystidia 30-45 x 9-18 jI,
vesiculose to utriform or fusoid-ventricose with obtuse apex (versiform), thinwalled, smooth, content not distinctive in either KOH or Melzer's. Cheilocystidia
18-42 x 10-17 L, clavate, vesiculose or fusoid-ventricose, thin-walled, smooth,
hyaline, content "empty." Caulocystidia absent or as scattered clavate hyphal
end cells.
Pileus cuticle a cellular layer 1-2 cells deep with many pedicellate cells in
the layer, the walls hyaline (including the pedicel). Subcutis also hyaline in KOH.
Clamps present. No amyloid reactions of any kind present in any tissue.
Type locality. Burt Lake at Colonial Point, Cheboygan County, Michigan.
Habit and habitat. Scattered on wet humus rich in lignicolous debris, June.
Distribution. Known only from type locality.
Observations. This species reminds one of a pale P. candolleana but has
pleurocystidia, grayer gills, and no color in the subcuticular region of the pileus
when sections are revived in KOH.
93. Psathyrella subnuda (Karsten) A. H. Smith, Contr. Univ. Mich. Herb. 5:
61. 1941.
Psathyra subnuda Karsten, Bidr. Finl. Nat. Folk 37: 234. 1882.
var. subnuda
Illust. P1. 47.
Pileus 3-6 cm broad, ovoid, or very obtuse, becoming broadly convex, plane
or with a broad low umbo, the margin sometimes recurved in age, but appressed
against the stipe when young, glabrous or with a very slight fringe of fibrils along
the margin, striatulate when moist, color "Prout's brown," "buckthorn brown,"