48 PRACTICAL FORESTRY 
thus hold the soil in place against the action of the 
waves and currents. 
A remarkable land-former is the mangrove-tree 
(Rhizophora mangle), which grows in great abun- 
dance along the shores of tropical seas. The seeds of 
this tree germinate while still attached to the parent 
plant, and instead of the seed, a young plant falls to 
the water, and is washed hither and thither by the 
waves and currents until it finds a foothold on some 
coral reef. There it grows and spreads, and soon 
forms a swamp in which vegetable matter quickly 
accumulates. Vast areas of shallow water between 
the Cuban mainland and the Isle of Pines are being 
rapidly converted into swamp by the action of the 
mangrove. The Bahama Islands and Florida keys 
consist of hundreds of small islands and reefs which 
are fringed with tangled masses of mangrove. After 
the little plants become thoroughly fixed, the birds 
and currents bring seeds of other trees from distant 
shores. As with the cypress, the mangrove projects 
roots into the air for the purpose of securing oxygen. 
Thousands of square miles have been wrested from 
the sea by the marvelous activities of this tree. 
Soon after large quantities of organic matter 
have been collected in the meshes of the mangrove’s 
roots, the coconut-palm, the fruits of which are car- 
ried long distances by ocean currents, finds a conge- 
