422 



POLLINATION OF FLOWERS 



Pollen is, in the case of a few aquatic plants, carried from 

 flower to flower by the water in which the plant grows. 



396. Insect-pollinated flowers. Most plants which requii 

 cross pollination depend upon insects as pollen carriers, 1 and it 

 may be stated as a general fact that the showy colors and mark- 

 ings of flowers and their odors all serve as so many advertise- 

 ments of the nectar (commonly but wrongly called honey) or of 

 the nourishing pollen which the flower has to offer to insect 

 visitors. 



Many insects depend mainly or wholly upon the nectar and 

 the pollen of flowers for their food. Such insects usually visit 

 during any given trip only one kind of flower, and therefore 

 carry but one kind of pollen. Going straight from one flower to 

 another with this, they evidently waste far less pollen than the 



wind or water must waste. It is 

 therefore clearly advantageous to 

 flowers to develop such adapta- 

 tions as fit them to attract insect 

 visitors, and to give pollen to the 

 latter and receive it from them. 

 397. Pollen-carrying appara- 

 tus of insects. 2 Ants and some 

 beetles which visit flowers have 

 smooth bodies, to which little 

 pollen adheres, so that their visits 



A, right hind leg of a honeybee (seen are often of slight value to the 

 from behind and within) ; B. the n -i -i , i n r 



tibia; i, seen from the outeide, flower, but many beetles, aU but- 



showing the collecting basket formed terflies and moths, and most 

 of stiff hairs. After Miiller , , -, -,. , ,-, 



bees have bodies roughened with 



scales or hairs, which hold a good deal of pollen entangled. In 

 the common honeybee (and in many other kinds) the greater 

 part of the insect is hairy, and there are special collecting 

 baskets, formed by bristle- like hairs, on the hind legs (Fig. 322). 



1 A few are pollinated by snails ; many more by humming birds and other 

 birds. * See P. Knuth, Handbuch der Bliithenbiologie, Vol. I. 



FIG. 322 



