PROBLEM 13 



39 



enlarged part at the base (not always easily seen; is the uvanj; 

 the stalk is the style; the tip, which is sticky, is called the Hlif^mn. 

 On this sticky surface pollen grains will grow. IIow \\<\si\\\ pollen 

 get to the stigma? 



Cut a cross section through the ovanj. Describe what you find 

 inside. These little 

 structures are called 

 ovules. Under cer- 

 tain conditions, which 

 we will later discuss, 

 a part of a pollen 

 grain will cause these 

 ovules to grow into 

 seeds. 



Fill out a diagram 

 like the accompany- 

 ing in yoiir notebook. 



Conclusion. — 1. What parts of the flower are essential for tlic 

 production of seeds? 



2. What are then the essential organs of a flower? 



Drawings. — 1. A flower from above. Label all parts. 



2. A stamen, showing all parts. 



3. A pistil, showing all parts. 



Problem 13: The cross-pollination of Jhnrrrs. 



Method. — Take a trip to a locality wlicrc flowers are a])uri(iant 

 and make a preliminary study of the relation of in.^ccts to flowers. 



Observations. — Notice whether the flowers are being visited 

 by insects. 



To what orders do these insects belong? 



Do bees visit flowers of one sort in succession, or of dilTerent 

 sorts? Make a careful study of this point by following a .single 

 bee or other insect. AVork this out in tlie case of a butterfly. 



Do insects seem to prefer any one color in flowers to another 

 color? Make careful o])servations on this i)oini. 



Can you discover any means by which the flower iniiiht affraef 

 an insect? Remember insects can probably smell and taste a.s 



