PLANTS THAT BUILD ISLANDS 125 



It is interesting to know that many small grasses 

 which appear to be only two or three feet high are 

 in reality often forty to fifty feet from their low- 

 est roots to the tip of their blades above the earth. 

 As each stalk of grass sends out numerous others,^ 

 each of which is covered with myriads of small 

 thread-like roots, it is not difficult to understand 

 how tightly bound the drift-sands become. These 

 living threads have sewed them together. The 

 sands blow over the grass, of course; but imme- 

 diately it begins to send out roots and to send up 

 stems. 



There are several species of the mangrove-tree 

 (Rhizophora) that have a unique way of building 

 islands. The appearance of the mangrove is such 

 that many strange superstitions have arisen regard- 

 ing it. By some of the natives on the coast of 

 Africa it is supposed to walk around in the water 

 at night; others regard it as the mother of the 

 earth, because it reclaims land from the sea. The 

 fantastic shape of this tree, because of its method 

 of branching, is very unusual. There are several 

 species ; two of them, common to Asia, Africa, and 

 Australia, allow their seeds actually to germinate 

 before leaving the parent tree. The fruit, when 

 mature, resembles a large inverted berry containing 

 one seed ; this fruit is well protected by seed-leaves, 



