The North American species of Psathyrella.

1972]

PSATHYRELLA

7

dish of the desiccant. The used (white) silica gel is reconstituted by heating in
an oven at around 2000 F. To do this spread the used gel on a cookie sheet and
place it in the oven with the door left open. If overheated the gel will break down.
Most dried specimens of Psathyrella species are as fragile as eggs and for
permanent preservation should be kept in cardboard boxes of suitable size for the
specimen rather than flattened and placed in paper packets as is done in many
herbaria. Some naphthalene flakes should be added to the box to repel insects, but
do not allow the flakes to cover the specimen. Before this is done, however, as
a precaution, the specimen should be fumigated. For most people this is most
easily accomplished by placing particles of paradichlorobenzene (paradow) in the
box and letting it stand (with the cover on) for about two weeks. Then remove
the remaining paradow and add the naphthalene flakes. NEVER MIX THE TWO
COMPOUNDS! Prepared in this manner and stored in a dry place, the specimen
will keep for years, but flakes should be added from time to time especially in
regions of high temperature during all or part of the year. If any insect damage
is noted remove the flakes and refumigate with paradow.
It is very helpful to keep a log-book in which one records the place and date
of collecting trips and the number assigned to each collection as well as the
tentative identification of the collection. When the specimen has been finally
identified, the name can be entered in the log-book following the number. The
collector's number on the field label will furnish an index number for the collection and can be used in place of a name on the envelope containing the negative
and also that containing the print.
The spore deposit. One is easily made by cutting off the stipe at the level of
the gills and placing the scarcely mature pileus (which should be perfectly fresh)
gills down on a piece of white paper. I often use a blank field label for this. Cover
with a container to prevent air currents from disturbing the process. When a
good "spore drop" has been obtained, as can be ascertained by the accumulation
of powder on the white paper, remove the pileus and allow the deposit to air-dry
for about 15 minutes. Then record its color on the 4 x 6 card carrying the description. Next fold the paper, with the deposit to the inside of the fold, and staple
this to the card. In this way the deposit is kept with the description. For small
caps, when set up for a spore deposit, place a small container over the setup and
add a drop or two of water to the inner surface of the container to keep the
humidity in the chamber high enough so that the pileus does not dry out before
spores are shed. If the pileus is more than 3 cm broad the simplest method is to
wrap the whole setup (the cap on the white paper) in waxed paper and place on
a table with the gills properly oriented for spore fall.
Specimens with spore prints prepared according to the above instructions are
worth sending to a specialist if the collector himself is not satisfied with his
attempts at naming them. Most collectors, however, will want to try to identify
their collections before drying them. If enough basidiocarps are available save
a few, and when your detailed study, as already described, is completed, go back
to the fresh ones and try to identify them with the literature you have available.
At the present state of our knowledge, this is likely to prove a frustrating experience in Psathyrella as well as in a number of other large genera. One usually finds
that before he can make a final decision, some features of the dried specimen must
be utilized. The ultimate aim in the study of mushrooms is to learn to know as
many species as possible at sight, but, until one has had great experience, it is
dangerous to assume you are right before you have checked the microscopic
features.