272 PSAMMOPHYTES SECT, x 



The foregoing remarks render it clear that shifting dunes in all lands 

 show a strong general likeness, and that similar sand-fixing plants always 

 occur. But the final result of the fixation varies very widely. In each 

 country there arises a xerophytic vegetation that does not essentially 

 differ from that occurring in other dry and sandy localities in the same 

 country. 



Dunes that have naturally been clothed with forest occur all the world 

 over, and in many places forest must have been compelled to contend 

 keenly against shifting sand. 



Here we must recall to mind the already-mentioned l tropical littoral 

 psammophilous forest, Barringtonia-association in eastern Asia, Coccoloba- 

 association in the West Indies, ' restinga ' on the shores of Brazil, and 

 other littoral forest on sandy soil. It has already been pointed out that 

 it is difficult to decide whether the forests owe their xerophytic character 

 mainly to the qualities of a sandy soil or to the salinity of this and to 

 the proximity of the sea. 



1 See p. 229. 



