The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Type locality. Ithaca, Michigan.
Habit and habitat. Gregarious on decayed hardwood stumps.
Distribution. Michigan.
Observations. The short, fat, subacute pleurocystidia, small narrow dark
cocoa-brown spores in KOH, white veil and cinnamon color of the dried pilei are
distinctive.
365. Psathyrella griseifolia A. H. Smith, sp. nov.
Pileus 1-3 cm latus, late conicus, glaber, fulvus; lamellae confertae, angustae,
griseae demum fuscae; stipes 6-11 cm longus, 2-2.5 mm crassus, glaber, deorsum
sordide brunneus; velum nullum; sporae 7.5-9x4.5-6 a; pleurocystidia 28-43x
10-15 u, late fusoide ventricosa; fibulae adsunt. Typus. Smith 61628 (MICH);
legit prope Le Gite, Quebec, Canada.
Illust. Text Figs. 817-820.
Pileus 1-3 cm broad, conic with a straight margin, expanding to broadly conic,
surface glabrous, moist, hygrophanous, margin faintly striate when moist, color
dull russet (near "Mars brown"), fading in streaks to dingy buff or pale tan.
Context very soft and fragile, concolorous with the surface, odor and taste mild.
Lamellae close, narrow, adnate but seceding, "drab" (gray), drying fuscous
(no cinnamon tone present), edges even.
Stipe 6-11 cm long, 2-2.5 mm at apex, equal or only slightly thicker at the
base, fragile, naked or a few faint white fibrils lower down, pallid above, pale
watery brownish below; no veil evident anywhere.
Spores 7.5-9 x 4.5-6 /u, smooth, apical pore distinct, shape in face view ovate
to elliptic, in profile obscurely inequilateral (plage area flattened somewhat) to
subelliptic, color in KOH dark chocolate-color in Melzer's dark reddish tawny,
wall about 0.4 K thick.
Basidia 4-spored, 24-28x8-11 Iu, short-clavate. Pleurocystidia scattered,
28-43x 10-15 I, broadly fusoid-ventricose with rounded to obtuse apex, thinwalled, smooth, content not distinctive (in either KOH or Melzer's). Cheilocystidia similar to pleurocystidia to clavate or merely subfusoid. Caulocystidia
versiform (Fig. 820), the ellipsoid to globose cells mostly with a slightly thickened
yellowish wall in KOH.
Pileus with a cuticle of a layer of vesiculose cells about 2 deep, the cells up to
50 u wide, walls thin and hyaline, content not distinctive. Subcuticular hyphae
tawny in KOH, the walls slightly thickened near the septa in many and pale
tawny in KOH, hyphae of remainder of trama also pale tawny in KOH at first.
Clamps present. No amyloid reaction in any tissue or cell.
Type locality. Le Gite, Laurentide Park, Quebec, Canada.
Habit and habitat. On sticks of alder, subcespitose to solitary, August.
Distribution. Canada: Quebec (Smith 61628, type).
Observations. The distinguishing features of this species are the elliptic to
subglobose caulocystidia with slightly thickened colored walls (as revived in
KOH), the short, broad and obtuse pleurocystidia, the rather wide spores, close
narrow gills, elongated stipe and fuscous-gray gills at maturity.
366. Psathyrella subsquamulosa A. H. Smith, sp. nov.
Pileus 2-4 cm latus, late convexus, spadiceus, ad marginem subsquamulosus,
glabrescens; lamellae pallidae, demum subspadiceae dein atro-brunneae; latae,