North American species of Mycena.

DIAGNOSTIC CHARACTERS

the taste is merely mild or slightly farinaceous (mealy). Certain
others, such as M. pura, are characterized by a distinct radishlike
taste and odor, but the characters do not always appear to be constant. The odors of many species are peculiar. In addition to those
with a raphanoid odor there are some in which the odor is alkaline
or nitrous; some in which it is strongly farinaceous or reminiscent of
raw cucumbers; some in which it resembles that of iodoform; and a
few in which it is decidedly fragrant or fruity (resembling that of some
esters). In the dried specimens of M. odorifera the odor persists for a
long time. In some the odor is strongest at the time the carpophores
are collected but fades quickly. Some have no odor when collected
but one soon develops which is very distinctive, as in MI. iodiolens.
In some that are normally distinguished by the presence of an odor,
odorless forms which apparently are genetically constant are known.
Since the majority of the species do not have a distinctive odor or
taste, the presence of one or both is an important character which
should be noted.
Some Mycenae tend to stain sordid reddish when cut or bruised,
or become spotted with sordid-reddish spots in age. The character
has been given some prominence in the literature. I have studied it
at every opportunity over a period of ten years and on the basis of
field observations have found that in some it is very constant under
all kinds of weather conditions, as it is in M. maculata, M. rubrotincta,
and M. viscosa. In many, such as M. rugulosiceps and M. galericulata, the gills become spotted only in extreme age or in wet weather.
In addition, some species have been described which appear to differ
only in this one character. M. hemisphaerica is characterized by the
absence of such spots and M. maculata by their presence. The former
is found chiefly on the wood of hardwoods; the latter, on wood of
conifers, an additional difference that should not be given much emphasis. It would be interesting to make a series of single-spore cultures from both and to try mating experiments. It is highly probable
that such culture work would go far toward elucidating the relationships of these two as well as those of similar species. Kiihner has
cited some interesting observations on this subject in his discussion of
M. strobilicola. Although I am inclined to question the value of this
color change as a character of taxonomic importance, it has been used
as an aid in recognizing species in several instances other than those
mentioned above. In such instances, however, the color change has
been correlated with some other secondary character.