NOTES ON AMERICAN CLADONIAS. 
BY BRUCE FINK. 
Since our western hemisphere surpasses the eastern in 
number of species and varieties of Cladonias and in forms 
peculiar to the hemisphere, the genus should have a special 
interest for the American student of lichens. Nevertheless 
our American descriptions have been for the most part 
quite inadequate and many of our determinations conse- 
quently incorrect. Cladonias are the most variable of all 
our higher lichens and therefore the most difficult to de- 
scribe definitely. The most variable characters are those 
which may be studied with the eye or with a good hand 
lens, yet the most careful observation, the best possible 
descriptions, and comparison with authentic specimens are 
all necessary to enable one to determine these plants with 
any degree of certainty. Size, form, color, lobing and 
branching and the presence or absence of cortex and soredia 
must be constantly kept in mind in the consideration of 
the horizontal thallus, and yet more in the study of the 
podetia. 
In actual determinations of Cladonias, the microscope 
need scarcely be used, except in instances where it is 
necessary to examine the thallus structure or the spores to 
make certain that one has not some species of such closely 
related genera as Baeomyces, Stereocaulon or Piloporus 
rather than a Cladonia. It is true that E. Wainio in his 
excellent Monograph, has seen fit to give a minute descrip- 
* tion of each species, even including the minute anatomy 
of the thallus of each species in great detail, but our in- 
vestigations indicate that these characters of minute 
morphology are so constant, in the Cladonias, as to be only 
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