202 ELEMENTS OF BOTANY. 



Floating on water is not, in temperate climates, as obvious 

 and important a means of carriage as that by means of the 

 wind, but it is often of great value, and in the case of the 

 cocoanut, with its light fibrous husk and waterproof shell, 

 serves to secure carriage for thousands of miles. It is inter- 



PiG. 184. —Portion of a Branch of " Russian Thistle." 



esting to notice that the first trees which appear on a coral 

 island, when it emerges above water high enough to support 

 the growth of trees at all, are cocoa palms, sprung from 

 cocoanuts which have floated perhaps half across the South 

 Pacific Ocean. 



