CHAPTER VII 



AQUATIC VEGETATION' 



Comprehensive studies of aquatic vegetation^ on the 

 lines followed in this book, have not yet been carried out 

 in this country; and consequently the material for a 

 systematic treatment of the vegetation scarcely exists. 

 For the sake of com.pleteness the subject has not been 

 omitted altogether, but the following pages must be 

 regarded rather as suggestive of the lines along which 

 future work may proceed, than as expressing a satis- 

 factorily established scheme of classification ^- 



The first and most obvious division of aquatic vege- 

 tation is into the vegetation of saltwater 

 saltwater. ^^^ *'^® vegetation of freshwater, for the 



presence of dissolved salt in any proportion 

 near that of seawater is well known to change completely 

 the aquatic flora. The vegetation of the sea is entirely 

 omitted from this book, though the " maritime " land 

 communities inhabiting the coasts and coming within the 

 zone of direct influence of the sea are dealt with in a later 

 chapter. 



In considering the vegetation of freshwaters we meet 

 with very wide differences in habitat, but nevertheless it 



' The aquatic vegetation of the Norfolk Broads is dealt with in 

 Chapter X, on account of its close relation to the vegetation of the 

 fen formation. 



' For some of the ideas contained in this chapter the Editor is 

 indebted to Dr C. E. Moss. 



