Seasides and Strand Plants 



Colletia overgrown with dodder, and the usual wild 

 Chilian bush, which occurs wherever the forest is trying 

 to grow up again. 



In the Landes of France, Psamma had not succeeded 

 in preventing the drifting in of seasand, which formed 

 great chains of dunes, some of them 250 feet in height, 

 interrupted by malarious marshes and lagoons. The 

 whole country was desolate and almost uninhabited. 

 Now it is a pine forest covering 1,500,000 acres, full 

 of villages and perfectly healthy. The change is due 

 to the intelligent way in which French botanists have 

 been able to assist Psamma in its usual undertaking. 



About a hundred yards from the shore, a paling is 

 first put up. It is of planks, but with intervals be- 

 tween them and about 3 feet above the ground. The 

 sand blows through the spaces and forms a ridge 

 behind the paling. Its accumulation is assisted by a 

 rough wattled fence. As the sand accumulates the 

 paling is raised and the fence renewed until there is 

 a ridge of sand some 60 feet high. This is now 

 planted along the crest with Psamma, which is looked 

 after from time to time until the dune takes such a 

 slope as is found to be permanent and stable. 



Then behind this great barrier the seeds of Pinus 

 maritima, whin and broom are sown down. It is in this 

 way that the huge forest has been created which has 

 now turned a desert into a healthy and valuable district. 10 



In the Dismal Swamp of the United States a very 

 similar colonisation seems to be carried through with- 

 out any help from man. Psamma is again the important 

 plant, and is aided by other grasses and Myrica (sweet 

 gale). 



Then Pinus taeda replaces them on well-settled dunes 

 and is eventually replaced by the ordinary deciduous 

 forest. 11 



167 



