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- 
Fia. 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. 
