Friesia IV, 1-2

-2-
R. H e s t e h a v e. In addition numerous species of mushrooms have
during the last few years been received for identification from many
Danish botanists and others interested in fungi. The names of these
collaborators will in many cases appear under the description of
t he species. In the preparation of thi s publication Professors N. ' .
Bu chwal d, K n u d J essen, and ø. Wi n ge have given valuable
assistance, and Mr. E . B r o c k m e y e r has revise d t he Latin diagnoses
of the new species.
C o Il e c t i v eS p e c i e s. When working on the sys tematics of
t he genus one soon discovers that, though new species have during
t he last fe w decades bee n segregated from the old ones (e. g.
Psalliota cæmpestris, P. aroensis, P. siloaiica, and others) , the latter
are still so rich in forms t hat it will re quire several years intensive
work before they can be fully investigat ed; they do indeed present
a peculiar contrast t o the narrowly defined species of moder n
authors. These collective species may with some justification be
introduced into popular books but should be dealt with by spe­
cialists in more detail. After careful and prolonged study, both in
the field and the laboratory, we find that they must be divided
up into separate units, whether we call them species, subspecies,
varieties, or forms. The author is not sure that he has found the
right designation in all instances (Cp. J a k o b E. L a n g e, Fl. Ag.
Dan. IV, p. 54).
G o o d M a t e r i a l f o r I n ves t i g a t i o n. In the description
or the identification of Psalliota species, it is necessary to have
young fresh fruit bodies, as the gills especially are apt to fade and
turn greyish a few hours after gathering because the dark spores
ripen so quickly that it is impossible to classify the red colour while
it is still vivid and pure, which is normally the case at the time
when the pileus expands. Other characters too (i. a. the smell and
the change of colour in the flesh or pellicle when touched or broken)
are easily lost if the fungi are left overnight, particularly in a warm
room. Mushrooms received by post are as a rule of little value for
painting or description, although they can of course be used for
microscopic examination. On the other hand, in the late, cool and
damp autumn, when the attacks of larvae have stopped, young
newly gathered fruit bodies can be kept fairly fresh for a couple
of days, if placed in the shade on a damp lawn.
The reddening Flesh and yellowing Surface of