North American species of Mycena.

252 NORTH AMERICAN SPECIES OF MYCENA

trama with a very thin adnate pellicle over the surface, the tramal
body made up entirely of inflated hyphal cells (the hypoderm), vinaceous brown in iodine below the pellicle.
Habit, habitat, and distribution.-Gregarious in and around clumps
of ferns (Polystichum munitum), on fern debris, or on the soil; Idaho
Washington, Oregon, and California. It was abundant in November
and December, 1935, after severe cold weather, but was found only
once during the warm season of 1937.
Material studied.-Smith, 3620, 3670, 3716, 3802, 9397, 16679.
Kauffman, September 8, 1922, Idaho. Stuntz, F 342. Gruber,
Oregon.
Observations.-The fragile nature of this species should be emphasized. It is very difficult to get it into the laboratory undamaged.
The delicate pubescent covering of the stipe, along with the fragility,
makes it readily recognizable. The hairs of the stipe are narrow,
elongated, delicate hyphae. The variability in the stature of the
carpophores is such as to prevent this species from being accurately
classified in either Filipedes or Fragilipedes, the old Friesian sections.
Small forms of M. fragillima may resemble specimens of M. debilis
or, if they have longer stems, M. subfusca. The spore size distinguishes it from the former, and the lack of a layer of filamentous
hyphae in the flesh of the pileus separates it from the latter. The
iodine reactions of the flesh also appear distinctive, but not much
emphasis should be placed upon this character. Actually, M. subfusca differs in many small characters. Its cheilocystidia do not
become elongated into a long, narrow neck, its stipe is glabrous even
under very moist conditions, its habitat is quite different, and the
pileus is not evenly colored.
Large forms of M. fragillima closely resemble the fruiting bodies
with long stipes which I have referred to M. plumbea, but differ in
being usually decumbent, and in having paler colors, slightly smaller
spores, pubescent stipes, and in the structure of the pileus. Apparently there is no pigment in the vacuoles.
117. MYCENA PECTINATA Murrill
Mycologia, 8: 221. 1916
Prunulus pectinatus Murrill, North Am. Flora, 9: 333. 1916.
Illustrations: Plates 40 B, 45 B; Text fig. 30, nos. 1-2.
Pileus (5) 10-20 (30) mm. broad, obtusely conic with an appressed
margin, becoming broadly conic and the margin often flaring, finally