124 THE HUMAN SIDE OF PLANTS 
cause of a volcanic upheaval, and such islands are 
usually stationary; but here, too, plants play their 
important part. A big rock rises out of the sea, 
drifting seaweed begins to lodge on it, sand and 
seashells soon are heaped upon it, all increasing 
the height of the island; more plants, especially 
grass seeds, drift to it; finally birds come and bring 
more seeds; perhaps cocoanuts think it a good rest- 
ing-place from their long sea voyages, and stop; 
the seeds of the binding-grasses start their work 
of binding the soil together; later even pine-trees 
spring up; and lo! a habitable island is the result. 
This ingenious binding and tying of the drift- 
sands by plants is done largely by means of their 
roots. And there are, in addition to the grasses, 
many small shrubs and trees which are engaged in 
this work. 
On the western coast of the United States there 
is a yellow lupin with exquisite pale-green leaves, 
and yellow blossoms which sleep at night. This 
lupin is usually one of the first settlers on a new 
island. Its long, fibrous, rope-like roots bind the 
drifting sands together, like so many long fingers; 
other seeds, drifting by, find a comfortable place 
to germinate and grow. And soon the island be- 
comes a substantial body of land because of the 
patient work of these plants. 
