FERTILIZATION 



of their own, must be carried by something from the anther 

 of one flower to the stigma of another. Two agencies are 

 active in this work, the wind and insects. Flowers which 

 depend upon insects for cross-pollination (i.e. pollination 

 resulting in cross-fertilization) must, as we can readily see, 

 have some means of attracting them. We find that flowers 

 do this by providing bright (or conspicuous) colors, odors, 

 or honey. Further, the flower must be constructed so that 

 it cannot readily be self-pollinated, and from this point of 

 view the different shapes of flowers must be studied. We 

 shall study some of these peculiarities under the following 

 heads : Irregular Flowers, Unsymmetrical Flowers, Coales- 

 cence, and Adnation, which are, in most cases, devices to aid 

 in securing cross-pollination. 



The wind-pollinated flowers are less complicated in struc- 

 ture, have no conspicuous color, no odor, and no honey. 



During our whole study of the flower, we must ask our- 

 selves how the flower is fertilized, i.e. whether it is cross- or 

 self-pollinated, whether insect- or wind-pollinated, and what 

 special devices are present to secure cross- or close-pollina- 

 tion or to prevent the one or the other. These things are 

 the keys for unlocking to us the mystery of the variety of 

 flower structure and coloration. 



