138 



FERTILIZATION AND POLLINATION 



In certain seasons, moreover, it confines 

 itself to a single species of plants. Bees are 

 very useful to the fruit-grower, wholly aside 

 from the honey that they make for him. 



283. Many flowers are pollinated by the 

 wind. Such flowers produce great quantities 

 of pollen, for much of it is wasted. They 

 usually have broad stigmas, which expose 

 large surfaces to the wind. They are usu- 

 ally lacking in gaudy colors and in perfume. 

 Grasses and pine trees are typical examples 

 of wind-pollinated plants. 



284. In many cases cross-pollination is 

 insured by the stamens and pistils being 

 in different flowers (diclinous, 274). When 

 the staminate and pistillate flowers are on 

 the same plant, e.g., oak (Fig. 228), beech, 

 c hestnut, 



hazel, walnut 

 (Fig. 190), 

 hickory, the 

 plant is mon- 

 oecious ("in 



one house")- When they are 



on different plants (poplar and 



willow, Fig. 229), the plant is 



dioecious ("in two houses"). 



Monoecious and dioecious 



plants may be pollinated by 



wind or insects, or other agents. 



They are commonly wind- 

 pollinated, although willows 



are often, if not mostly, in- 231 . Ear of maize , p roduct of the pi8 tii. 



Sect-pollinated. Some plants, late flowers fertilized by pollen borne 



. in the tassel, the whole enclosed m a 



as rye, insure cross-pollination husk or sheath. 



230. Indian corn, a 

 monoecious plant, 

 with staminate 

 flowers borne in 

 the tassel and 

 pistillate flowers 

 borne in the ear. 



