North American species of Mycena.

318 NORTH AMERICAN SPECIES OF MYCENA

specimens" I refer to those in which pleurocystidia are lacking or are
very rare. In California such odorless forms are sometimes abundant
on redwood logs during November and December. Their gills have
been observed to become stained with sordid reddish brown in age.
Such a change has been noticed only rarely in Michigan material; it
appears to be correlated with wet weather.
I have been unable to demonstrate that the presence or the absence of pleurocystidia is taxonomically significant in this species.
All gradations have been found in material collected in Michigan.
This was a distinct surprise because in other species of the genus, as
well as in most other gill fungi, the presence or the absence of pleurocystidia has proved to be a valuable taxonomic character.
The cheilocystidia vary considerably in shape. In some collections they are obtuse and with one or more fingerlike prolongations;
in others this type is found along with typically fusoid-ventricose
cystidia with pointed apices; and in still others the fusoid-ventricose
pointed type is the only one present. In general, the pleurocystidia
and cheilocystidia on any one cap are similar in size and shape. In
the form which Peck described as M. vexans, however, the pleurocystidia are narrowly fusoid and the cheilocystidia obtuse and more
or less branched.
Although the tissue of both gills and pileus gives the typical
amyloid reaction, I have found it to be an unreliable character. In
selecting specimens for iodine tests one should be careful to take only
those which have been properly dried.
After studying this species locally for a period of years, I believe
it is made up of a large number of races which are only beginning to
be differentiated morphologically. In their present state of incomplete differentiation they are not recognizable as distinct units of the
agaric flora and should all be grouped under one name. If one attempts to distinguish forms on the basis of the presence or the absence
of pleurocystidia, he can generally recognize four conditions: cystidia
absent, rare, scattered, or abundant. With these one might attempt
to correlate the odor and make a series of forms based on the strength
of the odor and whether pleurocystidia are present or absent, until
all the possible combinations have been made. Such a procedure
would be arbitrary and would only cause confusion.
154. Mycena incarnatifolia, sp. nov.
Illustrations: Plate 72; Text fig. 40, nos. 1-2 (p. 3290).