Fertilization of Flower,, 



15'J 



thousands of wheat plants and very many more thousands of the 

 flowers. If it were necessary for insects to transfer pollen to every 

 one of these flowers it would require swarms of them to accomplish 

 the work during the time the plants are in bloom, and it is very evi- 

 dent that we would either be overrun by insects or that many of the 

 flowers would remain unfertilized and there would be a very short 

 wheat crop. Hence it is for the advantage of man that the cereals on 

 which he depends so largely for his sustenance are anemophilous 

 instead of entomophilous. 



Many of our forest trees produce clusters of small inconspicuous 

 flowers with exserted stamens, as in the maples and elms, or their 

 flowers, and especially their staminate flowers are in aments whose 

 scales are much shorter than the stamens, as in the poplars, oaks, 

 hickories and birches. These characters indicate very clearly that such 

 trees are anemophilous. The indications are strengthened by the fact 

 that such trees usually put forth their flowers before they do their 

 leaves, or at least before their leaves are fully developed, an arrange- 

 ment which clearly favors the dissemination of the pollen by winds, 

 for the breezes play among the branches more readily and freely while 

 the leaves are yet unexpanded than they do afterward. 



In the tulip tree, Liriodendron tulipifera, the flowers are large and 

 highly colored and do not appear until the leaves are well expanded. 

 In the bass wood, Tilia Americana, and the horse chestnut, M&culw 

 Hippocastanum, the flowers are conspicuous by their colors, but they 

 are of small size. This, however, is remedied by their growing in 

 clusters and making up in numbers what they lack in size. 



In the flowering dogwood, Gornus florida, they are not only in clus- 

 ters, but also a large and showy involucre is added; evidently for the 

 purpose of making them more conspicuous, and in aiding in attracting 

 insects. The design in all these cases is so evident that one could say 

 with perfect confidence, upon seeing such flowers for the first time, 

 and without knowing that insects ever visited them, that they were not 

 fertilized by the agency of winds, but by some agent that could be at- 

 tracted by conspicuous colors. When to this is added a decided 

 fragrance, especially in such cases as the bass wood, whose flowers are 

 apt to be partly concealed by the foliage, the evidence of design becomes 

 stronger. If now we examine these flowers more closely and find that 

 deep down in their colored cups they secrete drops of honey or sweet 

 nectar, the natural and eagerly-sought food of many insects, the evi- 

 dence is complete. The botanist can assert positively that insects are 

 the pollen carriers for such flowers. He sees here the means by which 

 the flower secures the services of insects. It baits them with food. 



