122 



PLANT EELATIONS. 



plants, is known as pollination, and 

 the two chief agents of this transfer 

 are currents of air and insects. In 

 §77 the transfer by currents of air 

 was noted, snch plants being known 

 as anemophilous plants. Such plants 

 seldom produce what are generally 

 recognized as true flowers. All those 

 seed-plants which produce more or 

 less showy flowers, however, are in 

 some way related to the visits of 

 insects to bring about pollination, 

 and are known as entomophilous 

 plants. This relation between in- 

 sects and flowers is so important and so extensive that it 

 will be treated in a separate chapter. 



Fig. 130. A head of fruits of 

 burdock, showing the 

 grappling appendages. — 

 After Beal. 



