THE FLOWER 



213 



316 



317 



matic surface. It remains in this position till the anthers have 

 shed their pollen, then, as may be seen by examining an older 

 flower, the style begins to elongate, pushing up the pollen 

 that has fallen on the hairy outside of the closed stigma, and 

 forcing it out of the corolla tube, where it can be scattered 

 by insects among the other 

 flowers of the cluster. When 

 the pollen of its own floret 

 has been thus disposed of, the 

 stigma lobes open and curl 

 outward, ready to receive the 

 pollen from other flowers. 

 This arrangement is practi- 

 cally universal among plants 

 of the composite family ; can 

 you divine its object? It 

 will be shown later, that much 

 larger and stronger seeds are 

 produced when the pistil is 

 pollinated from a different 

 flower, or, better still, from a 

 different plant of the same 

 species ; hence, you see what 

 a useful adaptation this is. 



236. Nature of a composite flower. — It will be evident, 

 from the examination just made, that the daisy, dandelion, 

 sunflower, etc., are not single flowers, but compact heads 

 of small blossoms so closely united as to appear like a single 

 individual ; hence they are said to be composite, or com- 

 pound. They are the most numerous and widely dissem- 

 inated of all plants, comprising one seventh of the entire 

 flowering vegetation of the globe, and are regarded by 

 botanists as representing the most advanced stage of floral 

 evolution. Can you point out some of the adaptations to 

 which their success in solving the problems of plant life is 

 due? (164.) 



315 



Figs. 315-317. — Flowers of Arnica 

 montajm, showing successive stages in pol- 

 lination : 315, pistil just extruding from 

 anther tube, covered with pollen, but with 

 stigmatic surfaces closed; 316, stigma 

 opened and mature ; 317, stigma recurved 

 to receive pollen from its own or neigh- 

 boring anthers if foreign pollen has not 

 reached it. 



