The North American species of Psathyrella.

1972]

PSATHYRELLA

27

In summary, it also can be said that Psathyrella is one of the most homogeneous genera in the Agaricales, a fact first recognized by Quelet and later
reiterated by Romagnesi (1944). The species in it, though they can be recognized after critical study, are so similar that arrangement of them into groups
or lines to emphasize presumed relationships might be more misleading than
helpful. It seems to me, that for both Psathyrella and Coprinus, more studies
in culture relative to the behavior of such characters as the size of the germ
pore, thick-walled cystidia, hyphal incrustations, etc., through a number of
generations are highly desirable. Until we know more of the stability of these
features and their genetic basis, our classification is bound to be highly tentative.
ACKNOWLEDGMENTS
This project has been underway since 1935, and in the interval the author
has received aid in many forms from many sources. It is impossible now to
present a complete list, but this in no way detracts from the value of the contributions. My first acknowledgment must go to The New York Botanical Garden,
Bronx, New York, and to Dr. Fred J. Seaver, Curator of Fungi, for asking me
to undertake the work. In fact the original arrangement was for the completion
of the manuscript by 1941. Dr. Seaver, Dr. Donald Rogers who followed him,
and later Dr. Clark Rogerson all responded generously to calls for help in the
course of the investigation. The Peck collections at the New York State Museum
were made available to me by H. D. House, then State Botanist. Later, in
rechecking many items Stanley J. Smith was particularly helpful. The Atkinson
Collections at Cornell University were made available to me by Prof. H. M.
Fitzpatrick who also gave me personally conducted tours to Atkinson's collecting
areas around Ithaca. His time and effort in this respect were, and are, especially
appreciated.
At the University of Michigan, where the project was carried on as part of
my studies of the agaric flora of North America, I am deeply appreciative of the
time and effort spent by Prof. E. B. Mains, Director of the University Herbarium,
in discussions of problems in systematics and in supporting my requests for
funds for the prosecution of field studies. He was an ideal leader. Numerous
grants (nos. 58, 340, 1065 and 1417) in support of field work were received over
the years from the Faculty Research Fund of the University of Michigan, and
in later years from the National Science Foundation, Washington, D. C., for
work on a manual of the higher fungi of the western United States. Grants
G1063, G5988, G.23139, GB2902, GB4634, GB6876, GB6908, and GB6969 all
contributed to the work on Psathyrella and enabled the field work to be carried
out on a schedule rather than as an unconnected series of events.
The facilities of the University of Michigan Biological Station, first under
the directorship of Prof. A. H. Stockard, and later under Prof. F. K. Sparrow,
played a major role in the exploration of a transect extending from Ann Arbor
to the Lake Superior shore at Whitefish Point. This axis is now one of the
most thoroughly explored areas for agaricales in North America, and it has been
through this study that so much has been learned relative to the problems
of obtaining an adequate sample in floristic work on mushrooms.
The work in northern Michigan, in recent years has been greatly facilitated
by the Huron Mountains Wildlife Foundation, a subsidiary of the Huron
Mountains Club, Big Bay, Michigan. Largely through the interest and efforts
of Mr. Wm. Harris over many years, the holdings of the Club, which represent