North American species of Mycena.

DIAGNOSTIC CHARACTERS

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quently can be collected in great quantities in slashings. Some, such
as M. purpureofusca, that usually fruit on the wood of conifers, can
be found singly, springing from buried cones. Others habitually
occur on the remains of particular groups of higher plants. M. pterigena, for example, is found on dead fern fronds (those of the previous
year), and M. juncicola inhabits old sedge culms. Species living in
the needle beds under conifers often fruit in great profusion, whereas
those growing in wet mossy areas such as stream banks usually produce only a small number of carpophores. In general, the lignicolous
species appear to be somewhat restricted to wood of either conifer
or broad-leaved trees, but this separation cannot be used as a specific
distinction with much assurance. Peck has even reported finding
M. Leaiana on hemlock. For several species related to M. galericulata I have noted a marked ability to grow on either type of wood.
It can readily be seen that the species of Mycena exhibit all degrees
of affinity for higher plants, from the highly specialized type represented by 31. pterigena to the most generalized terrestrial type very
well represented by M. pura. Within these two extremes all stages
of specialization can be found. Many of the new species I have
described have been named for the substratum upon which they
usually occur, for example, M. madronicola, 31. piceicola, and M.
ulmicola.
Many of the terrestrial species show some affinity for habitats
produced or dominated by certain genera of our common forest trees.
M. clavicularis, M. monticola, AM. rosella, M. alcaliniiformis, M. metata, and M. pseudoclavicularis nearly always grow on the needle beds
of various pines. M. pseudoclavicularis appears to be a characteristic
species of the ponderosa-pine forests. M. parabolica and M. borealis
generally are found on the wood and debris of ponderosa and white
pine respectively, and occasionally give the impression of being terrestrial. M. tenax, M. piceicola, and 31. vulgaris frequently occur
on the needle beds under spruce. Differences caused by affinities
for particular sites are rather difficult to establish in the various mixtures of balsam-fir and spruce types, particularly in northern regions.
However, M. delectabilis is abundant in these habitats and also under
Douglas fir (Pseudotsuga taxifolia Britt.) in the West. M. atroalboides is common in bogs under black spruce in the northeastern
United States and also under silver fir (Abies grandis Lindbl.) and
Douglas fir in the West. M. galopus is one of the most characteristic
species of the redwood agaric flora of California, but in other parts