390 LIFE ON THE EARTH 



grain lights upon the stigma at its upper extremity. The 

 flowers of walnut and apple trees are fertilized by wind- 

 blown pollen. 



The pollen of very many plants, however, is carried 

 about by humming birds, bees, and other insects. As 

 the bee crawls into the flower to get the nectar at the 

 bottom, it brushes against the anther and 

 some of the pollen grains become at- 

 tached to it. These, later, are rubbed off 

 by the rough or sticky stigma of another 

 flower which the bee enters and thus the 

 flower is fertilized. The humming bird, 

 by reaching its long, slender beak down 

 into the long, narrow tube formed by the 

 corolla of the " wild honeysuckle " (Figure 

 124), brushes upon the stigma the pollen 

 grains it has obtained from another flower 

 and thus distributes pollen from flower to 

 flower. In no other way could these 



FIGURE 124 J 



plants be fertilized. 



The beautiful colors of flowers and the sweet nectars 

 that many of them secrete are the adaptations of the plant 

 for enticing insects to enter them and bring to 

 their stigma the pollen from other flowers, or 

 take from their anthers pollen needed to 

 fertilize another similar plant. 



FIGURE 125 



Some flowers are so constructed that only 

 certain insects can fertilize them ; the wild honeysuckle 

 requires the humming bird, the red clover the bumblebee 

 (Figure 125), and other plants, other kinds of insects. 

 Flowers of some varieties of plants cannot be fertilized by 

 flowers of a like variety. Certain varieties of strawberries, 



