90 LABORATORY PRACTICE 



CHAPTER XX 



IMPERFECT, INCOMPLETE, IRREGULAR, AND 

 UNSYMMETRICAL FLOWERS 



THE pattern flower which we have just studied was per- 

 fect, complete, regular, and symmetrical. We may now 

 study, hastily, several flowers, to understand what is meant 

 by the converse of these terms. 



I. Imperfect Flowers. Examine the flowers of different 

 plants of Begonia and notice : 



i. That some of the flowers of the same plant are provided 

 with stamens only and others with pistils only. 



3. These flowers are consequently imperfect, lacking one or 

 other of the essential parts ; viz. stamens in one case 

 and pistils in the other. 



3. Make notes and sketches; 



4. Where the two different kinds of flowers are borne on 



different plants, the plant is said to be dioecious, but 

 if they are borne on the same plant, as in Begonia, 

 it is said to be monoecious. (Do you know of any 

 dioecious plant?) 



5. Is close-pollination possible in a monoecious or a dioecious 



plant? Write down your answer and give your rea- 

 sons for it. 



6. Distinguish between the two kinds of cross-pollination 



which are possible in monoecious and dioecious 



