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. 



