96 HOW ARE ANIMALS AND PLANTS DEPENDENT? 



(2) The anthers are usually held high and exposed to the wind 

 when ripe. The common plantain and timothy grass are excellent 

 examples. 



(3) The pistil of the flower is peculiarly fitted to retain the pollen 

 by having feathery projections along the sides which increase the 



surface of the stigma. 

 ^ All our grains, wheat, 



rye, oats, and others, 

 have the typical 

 feathery pistil of the 

 wild grasses from which 

 they have been de- 

 veloped. 



(4) The corolla is 

 often entirely lacking. 

 It would only be in the 

 way in flowers that are 

 dependent upon the 

 wind to carry pollen. 



becrrino 

 pistillafe 



twfg 

 stccm.ino.te- 



Why are the flowers of the willow imperfect ? Explain how 

 cross-pollination might take place. 



easily accomplished by the wind 

 Name a flower that has no corolla. 



stomi.ncLte-' fl&&r 



Practical Exercise 13. 



Name five plants that have 

 a large proportion of pol- 

 len grains to each flower. 

 Study a diagram of a grass 

 flower. Why is pollination 

 What is the '''silk" of Indian corn? 

 (Look up in a good botany.) 



Imperfect flowers. Some flowers, the wind-pollinated ones in 

 particular, are imperfect ; that is, they lack either stamens or 

 pistils. In such flowers, cross-pollination must of necessity be 

 depended upon. In some trees, as the willow, staminate flowers 

 (those which contain only stamens) are developed on one plant, 

 and pistillate flowers (those which bear only pistils) on another. 

 Other species have staminate and pistillate flowers on the same 

 plant. The oak, hickory, beech, birch, walnut, and chestnut are 

 familiar examples. 



Practical Exercise 14. Show by means of diagram how pollination might 

 take place in the willow. 



