REVIEW ON POLLINATION 



135 



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

 What is its office? How frequent is it? What are entomophilous flow- 

 ers .' Anemophilous ? Exhibit 



or explain one of each. What 

 is the usual significance of ir- 

 regularity in flowers? Where is 

 the neetar borne ? What are 

 monoecious and dioecious plants .' 

 ( ileistogamous 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 prohibil the 

 stigma from receiving pollen 

 from its own flower, but the 

 iiei ter 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. Hear in mind that irregular and odd forms in flowers, -T r. > 1 1 lt 



perfume, bright colors, nectar, postulate Lnseul visitors; thai incon 

 spicuoue flowers with large protruding stigmas and much dry powderj 

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

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

 flowers are dichogamous. 



216. Common i>l ;e violet. The familiar 

 flowers are shown, natural size. The 

 corolla is sparred. Late in the season, 

 cleistogamous flowers are often borne 



on the surfa f the ground. A small 



en.- is shown al a. A rrearlj mature 

 pod is shown at 6. Both " and 6 are 

 one i bird natural si/.i\ 



