The North American species of Psathyrella.

1972]

PSATHYRELLA

223

lamellae latae, subdistantes, griseae, demum griseo-brunneae; stipes 1-2 cm
longus, 1 mm crassus, deorsum melleus; floccosus, glabrescens; velum subgranulosum; sporae 4-5 x 2.5-3 t; pleurocystidia 28-42 x 7-12 f, ventricosa-rostrata vel
fusoide ventricosa, acuta; fibulae adsunt. Typus. Smith 39274; legit prope
Tahquamenon Falls State Park, Michigan.
Illust. Text Figs. 404-408.
Pileus 8-12 mm broad, obtusely conic, expanding to campanulate, surface at
first white-frosted from remains of the outer veil and margin appendiculatedentate from outer veil remnants, soon glabrescent over all, color dingy yellowbrown ("buckthorn brown") before spores mature, near wood brown (gray-brown)
later. Context very thin and delicate.
Lamellae broadly adnate, subdistant, broad, grayish when young, becoming
grayish brown from the spores.
Stipe 1-2 cm long, 1 mm thick, pallid above, honey-color below, delicate, at
first coated with minute white flecks of veil material but soon glabrous.
Spores 4-5 x 2.5-3 /, smooth, apical pore evident, dark chocolate-color in
KOH, shape in face view ovate to elliptic, in profile subelliptic to obscurely beanshaped, wall about 0.2 ~ thick.
Basidia 4-spored, 5-6 J/ wide, clavate. Pleurocystidia 28-42 x 7-12 /, scattered,
fusoid-ventricose to rostrate, neck 2-3 K wide and apex acute, wall thin and
smooth, content not distinctive. Cheilocystidia similar to pleurocystidia (small),
neck generally not as narrow and apex more obtuse, at times narrowly clavatemucronate. Caulocystidia fusoid-ventricose to clavate or clavate-mucronate,
32-52x7-13 u, apex subacute to obtuse. Veil cystidia also present and subcylindric to subventricose with obtuse apex, 40-60 x10-14 /u, walls thin and
smooth, hyaline in KOH. Hyphae of stipe cortex pale cinnamon revived in KOH.
Pileus cuticle a layer 2-3 cells deep of vesiculose cells up to 35,u wide, walls
hyaline to weakly ochraceous in KOH and thin; subcuticular region pale tawny
in KOH, the pigment in the hyphal walls. Context hyphae hyaline, the cells
greatly inflated. Clamp connections present.
Type locality. Tahquamenon Falls State Park, Michigan.
Habit and habitat. Gregarious on hardwood logs, July.
Distribution. Known only from the type locality.
Observations. This is a very distinctive species because of its minute spores
and small pointed pleurocystidia.
181. Psathyrella carbonicola A. H. Smith, Contr. Univ. Mich. Herb. 5: 31. 1941.
Illust. 1. c. pl. 11; pl. 19, figs. 4, 6. P1. 42, fig. b; P1. 62; Text Figs. 409-411, 413.
Pileus (1.5-)3-6 cm broad, obtusely conic to convex at first, in age broadly
convex to plane, surface at first covered by superficial white fibrillose patches of
veil material, the scales appressed or somewhat recurved, glabrescent, surface
smooth or rugulose, color "chocolate" to "bister" when fresh, becoming nearly
"wood brown" and striatulate before fading, hygrophanous, when faded sordid
cinnamon-buff or near avellaneous. Context thin or thickish (up to 3 mm in large
pilei), tapering gradually toward the margin, very fragile, watery brown, odor
faintly disagreeable, taste mild.
Lamellae close to crowded, adnate, narrow, pallid brownish, bister (dark
yellow-brown) when mature but finally purple-brown and dried dark vinaceousbrown (near "bone brown"), edges whitish but even.
Stipe 3-7 cm long, 2-5(-6) mm thick, equal, tubular, cartilaginous, fragile,