North American species of Mycena.

EUMYCENA: TYPICAE

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bruised, margin concolorous with the faces; stipe 2-5 cm. long, 1-2
(3.5) mm. thick, strict and rigid, equal or slightly enlarged below,
hollow, very brittle, terete but often compressed in large individuals
and then longitudinally twisted-striate, densely pruinose over all at
first, base practically naked or slightly strigose, soon becoming
polished above, concolorous with the pileus or paler.
Spores 7-9 X 3.5-4 g, ellipsoid to subpyriform, smooth, weakly
amyloid; basidia four-spored; pleurocystidia scattered to rare, embedded, clavate, 26-34 X (5) 7-13 y, apices covered with short rodlike projections, hyaline; cheilocystidia similar to pleurocystidia,
abundant; gill trama homogeneous, sordid brown (weakly amyloid)
in iodine; pileus trama covered with a well-developed gelatinous pellicle (when revived in KOH), hypoderm fairly well differentiated, all
but the pellicle sordid brown in iodine; stipe having roughened caulocystidia near the apex.
Habit, habitat, and distribution.-Gregarious to scattered under
spruce and pine late in October or November in the vicinity of Ann
Arbor, Michigan. It usually fruits during periods of warm wet
weather between the heavy frosts of late fall. Hesler (5171) collected
what appears to be this species under hemlock at Highlands, North
Carolina, July 27, 1934.
Material studied.-Smith, 32-653, 77, 1167, 6157, November 16,
1931, Michigan. Hesler, 5171.
Observations.-As previously pointed out (Smith, 1927), the close,
thin lamellae of my collections are not in agreement with the Friesian
concept of the species. M. plicosa is rather distinct among the fragile
gray Mycenae having echinulate cystidia. Its stipe is so fragile that
it nearly always breaks at its point of attachment to the debris, even
when one is very careful in collecting it. The collector must dig
carpophores of this species out of the debris rather than pull them out,
as he does in gathering most gray Mycenae. The reddish-brown
stains on the gills appear to be an additional distinguishing character,
although it would not be surprising to find collections in which these
were not evident. When stains are present, one is likely to key the
fungus out along with the short-stiped form of M. atroalboides, a
species with which it has relatively little in common. The more
numerous pleurocystidia, as well as the rather thick pellicle, allow
dried specimens of M. plicosa to be readily identified. In fresh specimens the fragile stipe and particularly the late occurrence of the
fruiting bodies should distinguish it from variations of M. atroalboides.