POLLINA TION : HETEROSPOK Y. 



367 



the finger, and touch the upper surface of the labellum by thrusting it 

 between the latter and the style. The labellum curves quickly downward. 



671. Sometimes the bumblebees, after sipping the nectar, will crawl up 

 over the style in a blundering manner. In this way the flower may be pol- 





Fig. 468. 

 Pollination of the canna flower by bumblebee. 



Canna flower. Pollen on style, sta- 

 men at left. 



linated with its own pollen, which is equivr.lent to ?elf pollination. Un- 

 doubtedly self pollination does take place often in flowers which are adapted, 

 to a greater or less degree, for cross pollination by insects. 



