North American species of Mycena.

SUBGENUS MYCENELLA
IN THIS subgenus are placed all species with roughened or ornamented spores. All are grayish and Mycena-like in their appearance. The subgenus is made up of two unrelated sections. The
section Nodulosae is composed of a small number of very closely related species characterized by their finely pubescent stipes, large cystidia, and nodulose spores. The section Pseudoechinulatae contains
M. bisphaerigera and M. cineraria. The Nodulosae may very well
have been derived from the section Typicae of Eumycena and the
Pseudoechinulatae from the section Omphaliariae.
The species of both sections are very rare, and apparently are
more abundant during wet than during dry seasons. M. bisphaerigera
has been found most frequently just after an extended dry spell has
been broken.
KEY TO SPECIES
1. Spores nodulose............................................... 3
1. Spores echinulate or appearing so................................ 2
2. Spores with smooth outer wall, secondary wall thickened and with
numerous fine pores, which give it a falsely echinulate appearance,
outer wall amyloid......................... 231. M. bisphaerigera
2. As above, but spores not amyloid ("outer wall" absent); cystidia
present....................................... 3. M. cineraria
2. Spores truly echinulate, with very fine projections, nonamyloid
(see excluded species for M. farinacea Murrill)
3. Pleurocystidia simple or, at most, forked once at apex, often incrusted. 4
3. Pleurocystidia branched at apex; pileus 4-10 mm. broad; stipe not
radicating............................... 227. M. margaritispora
4. Stipe lacking well-differentiated pseudorhiza...... 228. M. trachyspora
4. Stipe with pseudorhiza......................................... 5
5. Pileus trama corticated by palisade of clavate to basidium-like somewhat irregular cells.................. 229. M. nodulosa
5. Pileus trama with thin pellicle, cells of which give off numerous short
rodlike projections............................ 230. M. bryophila
442