North American species of Mycena.

282 NORTH AMERICAN SPECIES OF MYCENA

Spores ovoid to ellipsoid, 7-9 (10) X 3-4 (4.5) pu, amylpid (reaction weak); basidia two- or four-spored, 22-24 X 5-6; cheilocystidia abundant, 19-25 (30) X 6-12 u, clavate to subcapitate with
the inflated portion covered with short or long prolongations, pleurocystidia absent or very rare, if present similar to the cheilocystidia;
gill trama deep vinaceous brown in iodine; pileus trama with a welldifferentiated pellicle, beneath it a distinct hypoderm (occupying
about half the trama) the cells of which have brown contents, the
remaining tissue filamentous and hyaline; stipe tissue vinaceouts brown
in iodine.
Habit, habitat, and distribution.-Densely gregarious on needle
beds under conifers or in sphagnum bogs in the late summer or fall.
It is common in the bogs of the northeastern United States and is
frequently found on needle beds under spruce. On the Pacific Coast
it is sporadic and often very abundant under Douglas fir and spruce.
I have found it in the United States in Michigan, Washington, and
California, and have examined material from Tennessee, New York,
and Idaho. Specimens from British Columbia in Canada have also
been studied.
Material studied.-Smith, 32-509, 32-510, 32-511, 32-512, 33-944,
33-945, 708, 750, 755, 863, 909, 923, 1250, 2510, 2598, 4882,: 7776,
7777, 7825, 7869, 8004, 8202, 8242, 8276, 14196, 14943. Atkinson,
14665. Beebe, 85, British Columbia, Canada. Hesler, 14086.
Gruber, Oregon. Slipp, UIFP, 2551, 2599.
Observations.-The colors of the pileus in this species nearly always
possess a tinge of cinnamon, which gives a very characteristic appearance to the dominant dark gray. In dry weather one often finds
large numbers of individuals in which there are no reddish spots.
At other times the gills may become entirely reddish brown, and the
stipe also may assume these colors. I have studied this point carefully, for I have followed the fruiting of this species regularly in one
bog near Ann Arbor over a period of ten years. The stipe is typically
short, as is shown in Plate 53 C. This is the most common form
along the Pacific coast. Peck's type consists of long-stiped specimens
from sphagnum, but, to judge from my own experience, this should
not be considered the "typical" form of the species. In many of our
sphagnum bogs the moss is not present under the dense clumps of
black spruce. M. atroalboides frequently fruits along the line separating the moss from the needle carpet under these trees or just at the
edge of the circle or arc formed by their outermost branches. Those