North American species of Mycena.

EUMYCENA: CORTICOLAE

71

in age sometimes "vinaceous buff" or grayish; flesh concolorous, thin,
pliant, reviving somewhat when moistened as in M. corticola, odor
farinaceous but soon fading, taste mild; lamellae broadly adnate but
becoming toothed or somewhat decurrent in age, subdistant to distant,
14-20 reach the stipe, narrow to moderately broad (9-2.5 mm.), color
"tilleul buff" to pallid at all stages, edges even; stipe short, 1-2 (3.6)
cm. long, about 1 mm. thick, equal above a basal subovoid bulb,
which soon disappears, tubular, delicately frosted over all at first,
soon polished and translucent, base pruinose and inserted on the bark
(as in M. corticola), concolorous with the pileus or paler, the apex
pallid.
Spores narrowly ellipsoid and pointed at one end, 9-11 X 5-6 L
from deposits, 7.5-9.5 X 4-5 g on dried material, amyloid; basidia
four-spored, 28-32 X 6-7 (8),; cheilocystidia forming a sterile band
along the gill edge or embedded and inconspicuous, 20-36 X 5-9 g,
clavate to capitate, upper portion varying from smooth to echinulate
or the apex prolonged into a much-branched, contorted neck; no
pleurocystidia; gill trama faintly vinaceous brown in iodine; pileus
trama made up of a thin pellicle of very narrow hyphae, beneath this
a region of enlarged hyphal cells with dull-brown contents (the hypoderm), the remainder of narrower hyphae forming a floccose filamentous tissue, all but the pellicle sordid vinaceous brown in iodine.
Habit, habitat, and distribution.-Densely gregarious by the hundreds on the scaly bark of old madrofia trees in open places after prolonged wet weather; Oregon. It was found late in November and
early in December.
Material studied.-Smith, 9224, 9286.
Observations.-Because of the large number of immature spores
in mounts of revived material the average size is smaller than that
obtained from material taken from a deposit, and for this reason
measurements from both deposits and dried material are included.
In most other species the size can be quite accurately determined
from herbarium specimens. The variability of the markings of the
cheilocystidia in this species is interesting. All of those shown in
text figure 3, no. 8, are from the type collection taken from a single
tree. The clavate-echinulate cystidia are most numerous and should
be considered typical. Smooth cystidia are usually found on young
gills or lamellulae. In age the echinulations on the clavate type may
become elongated into slender, crooked fingerlike projections. Sometimes the smooth cystidia elongate at the apex instead of becoming
echinulate.