CHAPTER XII 



ON PLANTS WHICH ADD TO CONTINENTS 



Lake Aral and Lake Tschad— Mangrove swamps of West Africa— New 

 mudbanks colonized — Fish, oysters, birds, and mosquitoes — Grasp- 

 ing roots and seedlings — Extent of mangroves — Touradons of the 

 Rhone — Sea-meadows of Britain — Floating pollen — Reeds and sedges 

 of estuarine meadows — Storms — Plants on ships' hulls — Kelps and 

 tangles in storms — Are seaweeds useless ? — Fish. 



THE way in which the savage, rugged, inhospitable 

 Britain of the Ice Age changed into our famihar 

 peaceful country formed the subject of the last 

 chapter. 



But plants do far more than cover the earth and render it 

 fertile, for some of them assist in winning new land from the 

 sea or from freshwater lakes. The Sea of Aral, for instance, 

 or Lake Tschad are rapidly becoming choked up by reeds 

 and other vegetation. Blown sand from the deserts around 

 is caught and intercepted by these reeds, so that fertile 

 pastures are gradually forming in what used to be the open 

 water of a deepish lake. 



By far the most extraordinary of all these plants which 

 form new land are the Mangroves. 



They are only found in the tropics or subtropical regions, 

 and are always along the seacoast. It is where a river ends in 

 a delta, dividing into intricate and confused irregularly 

 winding creeks, that the mangroves are especially luxuriant. 



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