WILLIAM A. SETCHELJL 



WATER PLANTS 



A STUDY OF AQUATIC ANGIOSPERMS 



BY 



AGNES ARBER, D.Sc., F.L.S. 



FELLOW OF NEWNHAM COLLEGE, CAMBRIDGE, 



AND KEDDEY FLETCHER-WAR R STUDENT OF THE 



UNIVERSITY OF LONDON 



WITH A FRONTISPIECE AND 

 ONE HUNDRED AND SEVENTY-ONE TEXT-FIGURES 



* ' ' 



V * * ^ ,\ 



CAMBRIDGE 



AT THE UNIVERSITY PRESS 



1920 



