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, 
