HOW PLANTS LIVE AND WORK. 331 



has three spreading lobes for receiving pollen. It should also be 

 noticed that each flower-bearing stalk stands well out from the 

 leaves, in order that the foliage shall not interfere with the access 

 of the pollen to the stigmas of the pistils. The male stalks hang 

 down from the lower part of the twig, and every stalk bears about 

 a dozen flowers. The male flowers have each from five to twelve 

 stamens, but they have no ovaries. The stamens produce pollen 

 in the usual way, and when they burst the wind blows the loose 

 pollen from the dangling stamens and scatters it in the air. Some 

 of the fine pollen dust is almost certain to be wafted to the 

 stigmas of the female flowers, and the pollen grains put out their 

 tubes and in due course fertilise the ovules. 



Now, although the flowers of the Oak are certainly pretty 

 enough, there is nothing showy about them. They do not go to 

 the trouble of pandering to the taste of bees and butterflies for 

 honey, and hence have no necessity for glaring advertisements. 

 In short, they have no needs for insects, and do not encourage 

 their visits. The gentle breezes of spring render them all the 

 assistance they require for fertilisation. It must not, however, be 

 supposed that the Oak does things " on the cheap." A little con- 

 sideration will show that a plant which depends on wind-fertilisa- 

 tion must of necessity produce a relatively enormous quantity of 

 pollen in order to ensure that fertilisation shall take place, in spite 

 of the loss of pollen which the method entails. 



Most of our forest-trees resemble the Oak in the fact that 

 they are fertilised by the aid of the wind. We can see that for the 

 process to be successful the trees must flower early in the Spring, 

 before the foliage has become thick enough to get in the way of 

 the pollen and prevent it from reaching the stigmas of the female 

 flowers. It is also necessary that the pollen may be easily 

 detached, and it is for this purpose that the male flowers of the 

 Oak and similar trees hang down in the familiar "catkin" fashion. 



In the cone-bearing trees — such as the Pine and Spruce Fir — 

 the ovules of the female flowers are naked ; that is, they are not 

 enclosed in an ovary, and the consequent absence of a stigma 

 makes a difl'erent arrangement necessary. The female cone 

 consists very largely of smooth scales, and the ovules are placed 

 on these scales near their bases. When the pollen falls on the 



