North American species of Mycena.

PSEUDOMYCENA: TENERRIMAE

49

course, that the fungus on beech mast in Denmark is different from
that on the same substratum in North America, but this does not
seem probable in view of the descriptions and illustrations.
There are several other forms in this group that deserve consideration. I have one collection on old oak leaves from near Ann Arbor.
It had all the characters of M. osmundicola except for the spores,
which are 8-10 X 3-4 j on four-spored basidia. There was a beautiful almost globular bulb at the base of the stipe. Its cheilocystidia
lacked the awl-shaped apical projections, and all other characters
were as given in the foregoing description.
At Pinckney, Michigan, E. B. Mains made one collection of a twospored form with spores 10-12 X 5-6 ju. He found the material on
debris of ferns in a bog. As in the previous collection, all other
characters were as given in the foregoing description.
At Ravenel Lake, Highlands, North Carolina (Hesler, 5170), and
in the Great Smoky Mountains National Park in a locality near Gatlinburg, Tennessee; a form was found (Hesler and Smith, 7471) in
which the stipe measured (1) 2-6 cm. long and had a rounded bulb
which disappeared as the stipe elongated. Its spores measure 7-9
(10) X 4-5 j, and were borne on four-spored basidia. The pileus was
a delicate yellowish-green color beneath the sugary coating and faded
to pale yellowish and finally white. Again, the cystidia are similar
to those of M. osmundicola. The hairs on the stem are longer than
usual for the latter, but when they are examined and compared under
the microscope, that difference does not appear taxonomically significant. This form was quite abundant in one locality along a stream
under rhododendrons near Gatlinburg.
The difficulties of working with these small fungi are such that
at present I am inclined to regard the collections mentioned above
as local variations about which we do not have enough information
to justify giving them separate taxonomic rank. I suspect that
M. osmundicola nearly always has a small bulb at first, and that its
absence is mostly a matter of the elongation of the stipe. The variations in spore size of 7-8, 7-9.5, or 8-10 M do not appear significant,
and the number of spores borne on a basidium has been shown to be
of no taxonomic value as a distinguishing character. The greenishyellow colors and long stipe of the Tennessee and North Carolina
collections may be more significant, and may serve to distinguish a
southern variety of the species.
The specimens Kauffman (1918) referred to M. setosa were found