North American species of Mycena.

12 NORTH AMERICAN SPECIES OF MYCENA

of the continent is found under either hardwoods or conifers. The
same thing is true to a lesser extent of M. scabripes. M. quinaultensis
and M. elegans show a pronounced affinity for stands of western red
cedar (Thuja plicata Donn.). The forests of Thuja occidentalis L.
of northern Michigan appear, however, to lack a characteristic species
of Mycena. M. alcalina frequently occurs on cedar, but, to judge
from my own experience, is more commonly found on larch. M.
laevigata has a strong affinity for the wood of larch in the western
United States, but can be expected to grow on almost any decaying
conifer log.
The various oak forests support a large fungous flora of both lignicolous and terrestrial species, a feature which may be considered
characteristic of them. M. algeriensis and M. Kauffmanii are nearly
always on or associated with either elm or ash. M. radicatella is
usually on the wood of either aspen or maple. M. floccipes, according
to my experience, is commonly found on the bark of hickory or elm
which has sloughed off fallen trees. Other instances of the association
of species of Mycena with certain higher plants are indicated in the
text.
Most species do not give a collector any clue to their presence
until the fruiting bodies are produced, but M. insignia is an exception.
It produces telltale whitish patches over the areas where the fruiting
bodies will appear. When collecting in different regions the mycologist frequently must adjust his ideas of habitats to new conditions.
In the wet, dense cedar forests of the Oregon coast, where some accumulation of dead needles often occurs on the lower branches of the
cedars, one can find M. rorida growing luxuriantly anywhere from six
to twenty feet above the ground. Ordinarily it occurs on the ground
under conifers.
The position which terrestrial species of Mycena occupy in the
life of a forest is difficult to ascertain, but without question they
fruit more abundantly at some stages of forest development than at
others. The lignicolous forms, of course, can be expected to occur
wherever the substratum and the environmental conditions are favorable. The species characteristic of the needle beds under conifers
appear to attain their optimum development in stands where ground
cover is lacking and a fairly deep layer of needles has accumulated.
In forests with a heavy ground cover the number of fruiting bodies
produced by a given Mycena as well as the number of species present
is likely to be small. This has been found to be true of hardwood