North American species of Mycena.

EUMYCENA: TYPICAE

267

126. MYCENA PUSILLA A. H. Smith
Mycologia, 31: 277. 1939
Illustrations: Plate 49 B; Text fig. 32, nos. 1, 3 (p. 268).
Pileus 5-10 mm. broad, convex to obtuse or with a slightly flattened disc, in age more or less expanded, plane or umbonate, margin
appressed against the stipe at first, often flaring and faintly scalloped,
striate to the disc when moist, surface hoary at first but soon polished,
lubricous when wet, glabrous, color pale watery gray with a whitish
margin when young, hardly paler at maturity, fading slowly to pallid
cinereous over all; flesh thin and membranous, rather pliant, pallid to
grayish, odor and taste not distinctive; lamellae ascending-adnate,
close, 18-20 reach the stipe, moderately broad (3 mm. ~) or somewhat
ventricose and quite broad for such a small fungus, the white edges
even and concolorous with the faces; stipe 2.5-4 cm. long, 1 mm.
thick, equal, tubular. hoary when young, soon polished and lubricous
but not viscid, tough, whitish above, darker grayish brown toward the
base, which is scarcely strigose.
Spores broadly ovoid to ellipsoid, occasionally slightly pearshaped, 7-10 X (4) 5-6 p, amyloid; basidia four-spored, 26-29 X
6-7 A; cheilocystidia clavate, hyaline, the enlarged portion covered
with short (occasionally branched) rodlike to filamentous projections,
26-30 X 7-12 u; no pleurocystidia; gill trama vinaceous brown in
iodine; pileus trama with a thick subgelatinous pellicle (25-40,u thick
in KOH) of very slender hyphae, the tramal body of somewhat enlarged hyphae, the cells of which become vinaceous brown in iodine.
Habit, habitat, and distribution.-In troops on moss and carpets of
conifer needles under Douglas fir in Oregon and northern California.
Not uncommon in the fall.
Material studied.-Smith, 7826, 7886, 7979, 8836.
Observations.-Small forms of many species of Mycena have been
found, and many of these appear to be genetically constant; at least
one sees them from year to year. These, because they resemble
normal fruiting bodies of the species in all other respects, have not
been given recognition in this work. It is very likely that certain
species produce large numbers of fruiting bodies when they fruit,
and that, given poor nutrient conditions, a large number of small
carpophores would be produced rather than a few of normal size.
M. pusilla does not appear to fall into this category because of the
additional characters which distinguish it from other terrestrial
Mycenae with roughened cystidia.