492 Introduction to the Study of Science 



too, certain willows and maples have blossoms which possess 

 much odor, but no petals. 



Exercise. The function of color and odor may be made quite 

 evident by disguising the color, the odor, and again both in several 

 flowers in the midst of the kind. Observe whether or not visiting 

 insects neglect the disguised flowers. Observe also whether insects 

 of a given kind, as the honeybee, visit all kinds of open flowers indis- 

 criminately, or follow only the flowers of a certain kind of plant. This 

 may be observed best in a garden or a field where there is a variety of 

 plants in blossom. If insects distributed pollen among different kinds 

 of flowers where it is useless, they would waste a large amount of 

 pollen, the most expensive of plant products. In the study of this 

 subject, consider such flowers as the buttercup, sweet pea, columbine, 

 petunia, pansy, skunk cabbage, wild orchids, and fruit tree blossoms, 

 such as the apple, the peach, or the orange, and also some night- 

 blooming flowers. 



It must be obvious that the primary function of the colors 

 and odors of flowers is not to please man's senses of sight and 

 smell, but to attract and secure the continued visits of insects. 

 That many flowers do give delight through their exquisite form, 

 color, and odor, is merely a happy coincidence. 



How plants select guests. The structures of flowers, which 

 are cross-pollinated through the agency of insects or other 



animals, such as the hum- 



a anthers with pollen. , . - , .. - 



" mm S bird and perhaps other 



birds, are well adapted to the 

 purpose (Fig. 155). The 

 sweet pea and red clover may 

 be taken as types of such 

 FIG. 155. Type of flower adapted to adaptation. The nectar of 



cross-pollination by insects. Large bees the gweet pea j g &Q l ocate d in 

 alight on I, brushing against s and a, thus *" 



transferring pollen from one flower to the base of the blossom that 

 another Small insects are excluded from ft bee j s certa i n to come in 

 nectar by n. 



contact with the stamens and 



is thus powdered with pollen, with which it pollinates many 

 stigmas as it continues its search for nectar. Red clover has 



