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 
Fic. 252. — Bees visiting Flowers. 
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 
