North American species of Mycena.

EUMYCENA: TYPICAE

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abruptly narrowed apex, broadly fusoid-ventricose or sometimes the
apex obtuse and furnished with two or more obtuse fingerlike projections, sometimes the apex forked or branched, 28-40 X 9-20,; gill
trama pale yellow or sometimes vinaceous red in iodine; pileus trama
with a rather thick pellicle and a well-differentiated hypoderm, the
remainder filamentous, yellowish or slightly vinaceous brown in
iodine.
Habit, habitat, and distribution.-Gregarious to subeespitose on
decaying wood of conifers and densely gregarious on humus under
conifers, particularly larch. I have found it most abundant in the
spring in northeastern North America, but it does occur during the
fall months as well. I have examined specimens from Alabama,
Tennessee, Pennsylvania, New York, Michigan, Colorado, Montana,
Washington, Oregon, and California in the United States and from
Nova Scotia, Ontario, and Manitoba in Canada.
Material studied.-Smith, 31-100, 32-2 (bispored), 32-3, 32-3a,
32-3b, 32-5, 32-5a-h, 32-6 (bispored), 32-13 (bispored), 32-18,
32-28, 32-57, 32-68, 32-73, 32-89, 32-100, 32-106, 33-50, 33-181,
33-529, 33-668, 33-1102, 657, 1301, 3609, 4673, 6216, 6247, 6756,
8102, 13087, 13335, 13593, 13826, 13956, 14079, 14201, 14230, 16181.
Atkinson, 13442, 14161, 24113. Burke, 1942, Alabama. Flett,
Washington. Hesler, 12945. Kanouse, Michigan. Kauffman, collections from Pennsylvania, New York, Michigan, Montana, Colorado. Ruth Macrae, Ontario. Mains, 32-120, 33-122, 33-180,
5079, June 9, 1933. Stuntz, F 413. Wehmeyer, 657.
Odorless form.-Smith, 3708, 3709, 3758, 3811, 3827. Atkinson,
22172, 22672, 24063, 24070. Overholts, 1791.
Observations.-This is perhaps the commonest species in the genus
in North America, but at the same time it is one of the most puzzling
because of the variability of its distinctive characters. Ordinarily,
the presence or the absence of a distinctive odor or of pleurocystidia
in Mycena is regarded as taxonomically significant, but in M. alcalina
as I have found it neither character appears to be sufficiently constant
to serve as an infallible mark of distinction. The odor is often weak
and detectable only if the flesh is crushed. Old specimens, or those
which have developed slowly, may seem to lack it entirely. I have
found occasional collections of perfectly fresh, rapidly developing
specimens with no odor and only a slight acidulous taste which were
identical in every other respect with typical material. By "typical