264 



FLOWERS 



to the plant ; they attract pollinators. In our own .climate 

 the humming birds, and in the tropics many other small 

 birds, are also attracted to flowers to get nectar, and they 

 aid in carrying pollen about. Among insects the bees are 



by far the most im- 

 portant pollinators. 

 Butterflies and 

 moths are also of 

 service to plants in 

 this way. 



As to the wind, it 

 is evident that no 

 odors or bright colors 

 are needed to attract 

 it. You would not 

 expect wind-polli- 

 nated flowers to be 

 fragrant or brilliant, 

 and they are not. 

 They are usually in- 

 conspicuous, and, if 

 they are noticed, 

 they may not be con- 

 sidered flowers at all. 

 (See Figures 100 B 

 and 106.) Now you 

 can see why it is com- 

 mon to think that grass and trees, except fruit trees and a 

 few others, do not have flowers. The flowers of grass and 

 of most trees are pollinated by wind, and are inconspicuous. 

 Pollination is a subject which needs a section to itself. 

 It is discussed in more detail in Section 63. It is mentioned 



Fig. 94 



Flowers and leaf of a common willow. 

 The two middle pictures show the clusters of 

 flowers which give rise to the name pussy willow. 

 Clusters like these are called catkins. The 

 upper catkin is composed of flowers which pro- 

 duce pollen but do not receive it (staminate 

 flowers). The flowers of the lower catkin re- 

 ceive pollen but do not produce it (pistillate 

 flowers). Of the two small pictures at the left, 

 the upper one shows a single staminate flower, 

 the lower a single pistillate one. 



