360 



FOUNDATIONS OF BOTANY 



432. Protection of Pollen from Unwelcome Visitors. — It 



is usually desirable for the flower to prevent the entrance 

 of small creeping insects, such as ants, which carry little 

 pollen and eat a relatively large amount of it. The means 

 adopted to secure this result are many and curious. In 



Fig. 252. — Bees visiting Mowers. 



At the left a bumblebee on the flower of the dead nettle ; below a similar 

 bee in the flower of the horse-chestnut ; above a honey-bee in the flower 

 of a violet. 



some plants, as the common catchfly, there is a sticky 

 ring about the peduncle, some distance below the flowers, , 

 and this forms an effectual barrier against ants and like 

 insects. Very frequently the calyx tube is covered with 

 hairs, which are sometimes sticky. How these thickets 

 of hairs may appear to a very small insect can perhaps 

 be more easily realized by looking at the considerably 



