The North American species of Psathyrella.

1972]

PSATHYRELLA

241

inflated cells 25-35 10-20 I,, forming an almost sterile band along the edge,
their walls hyaline to yellowish in KOH and thin to very slightly thickened
(0.5 /) and refractive, content not distinctive. Caulocystidia abundant and
versiform (Fig. 458).
Gill trama homogeneous, hyaline in KOH, hyphae subparallel. Pileus having
a cuticle consisting of a layer of vesiculose cells about 2 deep, their walls thin,
smooth and hyaline, the cell content not distinctive in KOH or in Melzer's. Clamp
connections present. In mounts in Melzer's no tissue or cells give a distinctive
reaction.
Type locality. Bavaria.
Habit and habitat. Commonly clustered on the ground or on bases of stumps
and trees of Populus species, spring and fall.
Distribution. Colorado, Idaho, Kansas, Michigan, Minnesota, New Mexico,
New York, North Carolina, Oregon, Vermont, Washington, Wyoming.
Observations. The color of the spore deposit, and also of the mature lamellae
in the fresh state, distinguish this species from P. sublateritia. In P. spadicea
the spore print, if a dense one is obtained, is some shade of chocolate-brown
rather than predominantly red as in P. sublateritia. This is reflected in a difference in degree in the color as seen under the microscope. In the color of the
spore deposit one is reminded of that found for Clitocybe benekii by Bigelow
and Smith (1970). There apparently is a difference in the caulocystidia between
P. spadicea and P. sublateritia, but it is difficult to be sure for either species
that an observer has seen all the variations which are present on either one.
Material examined. Colorado: Smith 51764. Idaho: Smith 53686, 73995,
9-26-68. Kansas: Haard 452. Michigan: Mazzer 4303; Smith 42053, 50253,
57381, 75531, 77500. Minnesota: Harrison 6634. New Mexico: Barrows 572,
1304, 1704, 1786, 1868, 2008. New York: Smith 424. North Carolina: Hesler
12294. Oregon: Smith 36699, 55581. Vermont: Shaffer 3534. Washington:
Smith 31225, 31422, 31428, 31429, 31437, 31827. Wyoming: W.B. Cooke 9-8-50;
Smith 35472; Solheim 4727.
199. Psathyrella sublateritia A. H. Smith, sp. nov.
Pileus (3-)5-10(-12) cm latus, convexus vel planus, glaber, demum rugulosus,
griseo-vinaceus demum lateritius vel vinaceo-brunneus; velum nullum; lamellae
confertae, vel subdistantes; pallidae demum lateritiae; stipes 6-10 cm longus,
(5-) 8-15 (-20) mm crassus cavus, fragilis, pallidus sursum pruinosus; sporae
in cumulis lateritiae; 7.5-9 (-10) x 4.5-5.5 g; pleurocystidia 40-60 x 10-20 /, late
fusoidea, maura 2-3 u crassa; fibulae adsunt. Typus. Smith 18303 (MICH);
legit prope St. Helens, Michigan.
Illust. P1. 66; Text Figs. 459-462.
Pileus (3-)5-10(-12) cm broad, obtuse to convex, with an incurved margin
at first, becoming broadly convex to plane or some with a low obtuse umbo,
in age the margin frequently uplifted and wavy, surface moist, glabrous, even
or rugulose over the disc and reticulate toward the margin, vinaceous-brown
"fawn color" in buttons, soon pallid on the disc, hygrophanous, at maturity
"wood brown" to "army brown" (dark avellaneous or tinged flesh-color in age),
fading to pallid or pale vinaceous ("pale vinaceous-fawn" to vinaceous-buff"),
brick red where dusted with the spores, often atomate when faded. Context thick
(5-9 mm), tapered evenly to the margin, pale watery grayish to pale vinaceous