22 



Fruits and Seeds 



brushed off others in the grass after carrying them some 

 way. Sheep pick up so many of these burrs that the 

 commercial value of wool is sometimes seriously injured 

 by it. Special machinery is used for getting rid of 

 them. The tiresome hooks with which they are covered 

 are the provision they have made to force animals to 

 help in their distribution. 



Some large tropical seeds make use of water as 

 their carrying agent. The best instance of this is seen 



Fig. 14. Three stages in the development of a winged Dandelion fruit. 



in the coco-nut. The coco-nut palm grows on the shore 

 of small coral islands, so that when the nuts fall from 

 the trees they are often washed away by the sea. They 

 are, however, wrapped in a boat-shaped husk that is 

 tough but very light (Fig. 13) ; and in this they float se- 

 curely until they are perhaps washed up on the shore of 

 another island, where the damp and sun together soon 

 make them germinate. This is why on newly formed 

 coral islands the coco-nut palm is often the first form of 

 vegetation to make its appearance. 



