North American species of Mycena.

4 NORTH AMERICAN SPECIES OF MYCENA

that genus. Grayish or dark-colored species with an incurved margin
and adnate gills are retained in Mycena if their pilei possess a differentiated hypoderm (this excludes such fungi as Collybia myriadophylla
and C. familia). All the white species of the section Mycenarii of
Omphalia have been transferred to Mycena as well as the colored
forms having cheilocystidia or amyloid spores (with the exception
of Omphalia campanella, 0. picta, etc., which are referred to the genus
Xeromphalina [Omphalopsis] by some authors and which in any case
form a series more closely related to Marasmius than to Mycena).
The series of Collybiae found on old cones-C. albipilata, C. myosura,
and the aberrant American C. conigenoides on Magnolia fruits-are
excluded from Mycena. The greatest difficulties in establishing the
limits of Mycena are encountered in the sections Hydropus and
Corticatae. In the latter the hypoderm is not differentiated, and
the margin of the pileus may be somewhat incurved. Because of
their Mycena-like appearance, they are included in Mycena, but
they can hardly be separated from the series of Collybiae with corticated pilei. Singer (1942) recognizes Hydropus as a distinct genus.
In keeping with the broad concept of Mycena employed here, it has
been included as a section. Although rather distinctive as a group,
its affinities appear to be in part in the section Lactipedes and in
part in the Omphaliariae. Critical studies need to be made on fresh
material of several species in order to determine their relationships
more clearly.
These limits differ from those given by Kiihner (1938) in excluding such species as Omphalia maura, Collybia myosura, and C. myriadophylla, and in including those with falsely echinulate spores.
HISTORY OF THE GENUS IN NORTH AMERICA
The first significant list of the North American species now placed
in Mycena was published by Schweinitz in 1822, the year following
the publication of Volume I of Systema Mycologicum, by Elias Fries.
This is of some interest because the work of Fries has since been selected as the starting point in agaric nomenclature. Schweinitz
listed under the generic name Agaricus such well-known species as
M. galericulata, M. polygramma, M. haematopus, M. epipterygia,
M. elegans, M. stylobates, M. vulgaris, and M. corticola. Some which
are less common and some now referred to Marasmius, as well as to
other genera, were also included. In 1834 Schweinitz published a
more extensive list of the North American species.