VEGETATION OF THE SALT MARSHES. 



361 



entirely. Thus, just above that poinl on the Nansemond River near 

 Suffolk where the water begins to be normally fresh, Spartina }><>hj- 

 stachya and Scirpus americanus are the only remaining salt-marsh 

 species, and such normally fresh-water plants as Sagittaria lanci/olia, 

 Ponlederia, Polygonum hydropiperoides, Typha latifolia, and Zizania 

 aquaticu form the bulk of the association at the water's edge. It is 

 probable that the last-named group of species can endure brackish 

 water at times, while, on the other hand, as Contejean has shown, 1 

 most "salt-loving" plants are not really dependent upon the presence 

 of salt in their substratum. It is probable that some salt-marsh spe- 

 cies find the silly or clayey soil of the marshes, which is rich in 



Fn; 



Salt uiarsli covered with Spartina atricta maritima. 



organic matter, more indispensable than the sodium chloride which it 

 contains. 



Several associations of species, in each of winch one species almost 

 always strongly predominates, may be distinguished in the salt-marsh 

 formation, although here as elsewhere sharp lines can rarely be drawn. 

 The most important of these will be noted. 



Spartina strirta association. — This assemblage, in which thatch y 

 grass, Spartina striata maritima, is often the only, and always by far 

 the most' important species, occupies the immediate edge of the water 

 along creeks and estuaries, sometimes as a mere fringe, sometimes 

 covering areas of considerable width (fig. 57). It- prefers places 



Geographic Botanique, p. 94. 



