KEVIEW ON POLLINATION 



135 



by the word dehiscence? What do you understand by dichogamy' 

 What is its oflfice? How frequent is it? What aieentomophilous flow- 

 ers ? Anemophilous ? Exhibit 



or explain one of each. What 

 is the usual significance of ir- 

 regularity in flowers? Where is 

 the nectar borne ? What are 

 monoecious and dioecious plants? 

 Cleistogamous flowers? 



Note. — The means by which 

 cross-pollination is insured are 

 absorbing subjects of study. 

 It is easy to give so much time 

 and emphasis to the subject, 

 however, that an inexperienced 

 observer comes to feel that per- 

 fect mechanical adaptation of 

 means to end is universal in 

 plants, whereas it is not. One 

 is likely to lose or to overlook 

 the sense of proportions and to 

 form wrong judgments. 



In studying cross-pollina- 

 tion, one is likely to look first 

 for devices which prohibit the 

 stigma from receiving pollen 

 from its own flower, but the 

 better endeavor is to determine 

 whether there is any means to insure the application of foreign pol- 

 len ; for the stigma may receive both but utilize only the foreign 

 pollen. Bear in mind that irregular and odd forms in flowers, strong 

 perfume, bright colors, nectar, postulate insect visitors; that incon- 

 spicuous flowers with large protruding stigmas and much dry powdery 

 pollen postulate wind-transfer; that regular and simple flowers de- 

 pend largely on dichogamy, whether wind- or insect-pollinated. Most 

 flowers are dichogamous. 



ne. C )tninon blue violet. The fnmUiar 

 flowers are shown, iiiitural size. Tlie 

 corolla is spurred. Late in the season, 

 eleistogamous flowers are often borne 

 on the surface of the ground. A small 

 one is shown at a. A nearly mature 

 pod is shown at 6. Both a and b are 

 one-third natural size. 





Funuelform corollas 



