The North American species of Psathyrella.

1972]

PSATHYRELLA

171

Basidia 20-26 x8-9 A, clavate, 4-spored, hyaline in KOH. Pleurocystidia
scattered, 30-48 x 10-15 Iu, fusoid-ventricose, apex obtuse to subacute (very acute
according to Parker), thin-walled, smooth, hyaline in KOH. Cheilocystidia similar to pleurocystidia varying to having a very narrowly acuminate apex, some
saccate cells also present, these hyaline or at the base ochraceous.
Gill trama regular, dark rusty brown in KOH. Pileus with a cuticle formed of
a palisade of inflated clavate to subsaccate nearly hyaline cells; the context of
interwoven dark rusty brown hyphae in KOH.
Type locality. St. Charles, Missouri.
Habit and habitat. Gregarious on the ground along a river bank.
Distribution. Idaho, Michigan, Missouri.
Observations. As Smith (1941) pointed out, the microscopic features readily
distinguish the species from P. hymenocephala.
Material examined. Idaho: University of Idaho For. Path. Herb. 3577.
Michigan: Smith 11072, 15423.
127. Psathyrella subtenacipes A. H. Smith, Mycologia 42: 132. 1950.
Illust. 1. c. figs. 20-i, 21-a, b. Text Figs. 293-295.
Pileus 1-2.5 cm broad, obtusely conic, expanding to plane or slightly umbonate,
surface moist and hygrophanous beneath a coating of white outer veil fibrils so
thin it does not obscure the ground color, ground color pale cinnamon-brown to
clay color moist, fading to cinnamon buff on the disc and pinkish buff elsewhere,
glabrescent or remaining slightly silky, margin appendiculate at first. Context
very thin and fragile, watery brownish fading to nearly pallid, odor none.
Lamellae close to nearly subdistant, bluntly adnate, moderately broad, pallid
young, near hair brown in age.
Stipe 3-4.5 cm long, 3-3.5 mm at apex, slightly and evenly enlarged downward, hollow, cortex pallid and fibrous, not distinctly fragile for this genus, white
but dull, more or less evenly appressed fibrillose from remains of the veil (no
zones or scales present).
Spores 7.8-9.5 x 5-6 I, smooth, apical pore small and apex rounded, shape in
face view ovate to elliptic, in profile obscurely inequilateral to subelliptic, color
in KOH bister slowly darkening to near "mummy brown" (very dark brown with
no reflection of violet), in Melzer's reddish tawny to pale bay, wall about 0.3 -0.4 F thick.
Basidia 26-30x 7-10 /j, spored, narrowly clavate, hyaline in KOH. Pleurocystidia 50-70x 10-15 A, abundant, ventricose-rostrate, the neck 3-4 u wide and
flexuous, apex subacute to obtuse, wall smooth, thin and hyaline, cell content in
H2O when fresh showing a large globule, in KOH fresh or revived perfectly
homogeneous, in Melzer's with a central amorphous mass not completely reviving and yellowish hyaline in color (reminding one of the content of chrysocystidia
as revived in KOH). Cheilocystidia generally similar to the pleurocystidia as
revived but smaller and more clavate-mucronate. Caulocystidia versiform from
a basic clavate type, thin-walled, smooth, hyaline, 30-56 x 9-18,u.
Gill trama hyaline in KOH, regular, cells smooth, with thin walls. Pileus
cuticle of clavate to vesiculose cells 2-3 cells deep, the walls smooth, thin and
hyaline, the content not distinctive. Tramal hyphae in region of subcutis dingy
tawny and with some incrusting material over the walls as revived in KOH.
Clamp connections present. No distinctive reactions on any tissue as revived in
Melzer's.