The North American species of Psathyrella.

1972]

PSATHYRELLA

369

bluntly adnate but soon seceding, dark rusty brown at maturity, edges even and
concolorous.
Stipe 4-5.5 cm long, 2.5-3 mm thick at apex, slightly and evenly enlarged
downward, straight or flexuous, very fragile, whitish, apex slightly fibrillosescurfy, the lower portion with scattered loosely adhering fibrils, probably the
remains of a thin partial veil.
Spores 7-9.5 x 4-5 t, smooth, apical pore small and often bulging slightly
(as revived in KOH), apex appearing truncate in some, shape in face view ovate
to (rarely) elliptic, in profile ovate to somewhat inequilateral, color in KOH
dark cocoa-color soon becoming dark chocolate, in Melzer's reddish tawny to
bay, wall about 0.4 /u thick.
Basidia 4-spored, 18-22 x 7-9 u, short-clavate, hyaline in KOH. Brachybasidioles present on mature hymenium. Pleurocystidia 40-65 x 10-15(-17) ~,
often arising in the gill trama, fusoid-ventricose with obtuse to rounded apex,
wall thin, smooth and hyaline, content not distinctive. Cheilocystidia either
fusoid-ventricose and 32-40 x 9-12 M or clavate with the wall slightly thickened
and yellowish as revived in KOH, the latter 14-18x8-11 j. Caulocystidia not
found.
Gill trama regular, dull chocolate-brown when first revived in KOH but
becoming pale sordid brownish. Pileus trama of interwoven dull chocolate-brown
hyphae soon fading to pale dingy brown (in KOH). Cuticle of pileus formed of
vesiculose hyaline cells one cell deep and some clavate cells present. Clamps
present.
Type locality. Near Lake Mills, Olympic Mountains, Washington.
Habit and habitat. On alder logs.
Distribution. Oregon, Washington.
Observations. The pink tone on the pileus margin in age, the ovate spores,
the presence of brachybasidioles, and the short broad basidia are distinctive.
Material examined. Oregon: Smith 24729. Washington: Smith 14268 (Type).
343. Psathyrella lauricola A. H. Smith & Hesler, Jour. Elisha Mitchell Soc. 62:
184. 1946.
Illust. l.c., fig. 1: I, J. L; 2: A. Text Figs. 743-745.
Pileus 1-2.5 cm broad, obtuse to convex, the margin appressed at first, surface
glabrous, not conspicuously striate, when moist "snuff brown" or more yellowish
on the disc (sordid ochraceous), the disc remaining tinged with ochraceous but
the remainder soon grayish and finally blackish umber, hygrophanous fading to
sordid cinereous on the margin and buff on the disc, conspicuously atomate when
fading. Context very thin and fragile, odor and taste not distinctive.
Lamellae adnate, subdistant, broad, blackish brown, edges whitish.
Stipe 3-5 cm long, 1.5-2 mm thick, equal, white, sparsely fibrillose, tubular,
rather firm.
Spores 8-10 x 4-5 I, smooth, apical pore distinct and apex narrowly truncate,
shape in face view elliptic to rarely narrowly ovate, in profile elliptic to very
obscurely inequilateral, color in KOH near "mummy brown" (blackish brown),
blackish brown in water mounts of fresh material, in Melzer's tawny-red to bay,
wall about 0.3 ~/ thick.
Basidia 14-17 x 7-9, 4-spored, hyaline in KOH. Pleurocystidia (36-)44 -62 (-70) x 8-12 t, subcylindric with broadly rounded apex to somewhat utriform,
wall thin, smooth and hyaline, cell content not distinctive in KOH or Melzer's.