The North American species of Psathyrella.

Nov. 1972 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 24: 1-633

THE NORTH AMERICAN SPECIES OF PSATHYRELLA 1
ALEXANDER H. SMITH
University of Michigan, Ann Arbor
INTRODUCTION
History
In contrast to many of the large genera of the Agaricales, such as Lactarius,
Russula, and Cortinarius, which have been recognized as homogeneous groups of
species since very early times, the assemblage of species here grouped under the
name Psathyrella was scattered through many different groups of Agaricus (in the
sense of Fries, 1874). These groups were recognized as genera by Saccardo (1887),
but all contained, in addition to species now placed in Psathyrella, many belonging in other genera. Psilocybe, Stropharia, and Hypholoma, for instance, all contained species now grouped in the Strophariaceae in addition to the element
belonging in Psathyrella. Quelet (1886) was the first to make a serious attempt
to bring these discordant elements from the various genera together into one genus,
to which he gave the name Drosophila. This concept and name were accepted by
Kiuhner and Romagnesi (1953).
S. F. Gray (1821) recognized the genus Prunulus and placed in it Agaricus
gracilis, the species now accepted as the type of Psathyrella. In Prunulus he also
placed such species as Prunutus denticulatus [Mycena pelianthina (Fr.) Quelet],
a white-spored fungus. Prunulus was subsequently used by Murrill (1916) in
place of Mycena, and to my knowledge, the name has had no further application
of significance for dark-spored fungi.
Fries (1838) recognized Psathyrella as a group for certain dark-spored species
of Agaricus, but other related species were parceled out into other groups of
Agaricus such as Psilocybe, Psathyra, etc. as mentioned above. Saccardo (1887)
merely used the Friesian groups at the generic level.
Singer (1951, 1963) following Quelet's work of 1886 placed the genus in perspective in an overall classification of the Agaricales, and made some order out
of the nomenclature. That his infrageneric classification was found to be inadequate for the genus in the present study is in direct proportion to the number of
species studied by each of us. But as a result of Singer's efforts Psathyrella
became recognized as one of the major genera of the Agaricales, a recognition
long overdue. Kiihner & Romagnesi (1953) in their descriptive key contributed
1 Publication of this paper was financed by National Science Foundation Grant
No. GN-671.
1