The Subaerial and Freshwater Algal Flora 
of the Tropics. 
A Phytogeographical and Ecological Study. 
BY 
F. E. FRITSCH, D.Sc., Ph.D., F.L.S. 
Assistant Professor of Botany, University of London, University College. 
i. Introductory. 
E VER since Botany became an independent science the tropics have 
attracted numerous specialists, who have dealt with one or other 
aspect of the tropical flora. These regions of the world provide so many 
striking problems, that many of them, although subsequently recognized 
as evident enough in our parts of the world, were first noticed and studied 
in the tropics. The science of ecology in particular received its first 
stimulus from tropical observation, and until quite recent years we were 
better informed about the conditions of vegetation in many parts of the 
tropics than in our own country. At a fairly early period we find botanists 
devoting a little attention to the tropical algal flora, but the apparent 
similarity between the freshwater Algae of the tropics and those of our 
parts did not encourage extensive observation in view of the numerous 
more striking problems to be solved. It was only in the seventies and 
eighties of the last century that a marked tendency became evident to 
collect more extensive data regarding tropical Algae, and this has since 
then led to the publication of quite a number of algal floras from diverse 
parts of the tropics. The latter are mainly due to the labours of Nordstedt, 
Lagerheim, W. and G. S. West, Schmidle, Mobius, De Wildeman, and 
Lemmermann, although, as the bibliography at the end of this paper will 
show, a large number of botanists are responsible for occasional papers on 
this subject. 
The general result of this work has been to show that there is a great 
degree of similarity between the algal flora of the tropics and that of other 
parts of the world. This is indeed what was to be expected in view of the 
fact that most of the Algae belong to the biological group of aquatics, and 
[Annals of Botany, Vol. XXI. No. LXXXII. April, 1907.] 
S 
