The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

[VOL. 24

Type locality. Algiers.
Habit and habitat. Cespitose-gregarious on sand dunes, December.
Distribution. California.
Observations. This species has wider spores than P. arenulina and pleurocystidia are reasonably abundant though not "volumineuses (x 15-22)" as indicated by Kiihner & Romagnesi. This point deserves further study. In appearance
the dried basidiocarps resemble those of the Strophariaceae more than those of
any other Psathyrella I have examined. Singer (1968) comments on the spore size.
The Californian collection establishes that variants with spores up to 14 KU long
occur in both Europe and North America.
Material examined. California: Smith 56813.
316. Psathyrella alluviana A. H. Smith, sp. nov.
Pileus 1-3.4 cm latus, campanulatus, glaber, cinnamomeo-brunneae demum
umbrosus, demum rugoso reticulatus, valde atomatus; contextu brunneus; lamellae latae (6-10 mm), confertae, brunneolae demum atro-brunneae; stipes 8-12 cm
longus, 1.5-2.5 mm crassus, glaber, pallidus deorsum demum ochraceus; sporae
10-12.5(-13) x5.5-7,u; pleurocystidia 46-70x8-12(-14),/, anguste fusoide
ventricosa, ad apicerum obtusata vel subacuta; fibulae adsunt. Typus. Smith
19272 (MICH); legit prope Government Camp, Mt. Hood, Oregon.
Illust. P1. 78, fig. f; Text Figs. 677-681.
Pileus 1-3.4 cm broad, conic-campanulate or conic-umbonate with a flaring
margin, glabrous, hygrophanous, "cinnamon-brown" when moist, becoming umber
over all except the disc, margin crenate, fading to grayish over the marginal area
and ochraceous over the disc or becoming ochraceous throughout, when faded the
surface very conspicuously but finely radially reticulate or wrinkled, the wrinkles
forking and anastomosing, very atomate to appearing almost furfuraceous, no veil
remnants present. Context very thin and exceedingly fragile, concolorous with the
surface, odor none.
Lamellae broad (6-10 mm) subdistant to close, adnate, soon seceding, pallid,
to pale brown to black, edges slightly crisped at times in age.
Stipe 8-12 cm long, 1.5-2.5 mm thick, tubular, glabrous, pallid to white
becoming dingy yellowish at the base, exceedingly fragile.
Spores 10-12.5 (-13) x 5.5-7 /u, smooth, apex truncate from a distinct broad
apical pore, shape in face view oblong to elliptic, in profile subelliptic to obscurely
inequilateral, color in KOH soon dark chocolate-color, in Melzer's dark reddish
tawny, wall about 1 thick.
Basidia 22-25x 10-12 1u, 4-spored, clavate, hyaline in KOH. Pleurocystidia
scattered to numerous, narrowly fusoid-ventricose, neck elongated, apex obtuse
to subacute, wall hyaline, smooth and thin, cell content not distinctive in KOH or
Melzer's, 46-70 x 8-12 (-14) /u. Cheilocystidia 28-42 x9-14 /, fusoid-ventricose
with obtuse to subacute apex, thin-walled, some saccate cells also present.
Caulocystidia similar to pleurocystidia to subcylindric, scattered, more variable
in size than the latter.
Gill trama interwoven, dark chocolate to cocoa-color in KOH, pigment
incrusted on the hyphae, subhymenium cellular and also slightly colored (in
KOH). Pileus trama dark cocoa-color fading to yellow-brown, pigment conspicuously incrusted on the hyphae. Cuticle of pileus of vesiculose to pedicellate
cells not arranged in a distinct palisade but the layer more or less one cell deep,
the pedicels of some slightly thickened and vinaceous-brown to yellow-brown in