io8 



MORPHOLOGY 



style is short and the stamens long; but the short 

 styles and the short stamens, as well as the long 

 styles and the long stamens, although they belong 

 to different flowers, are of the same height respec- 

 tively. In these flowers, pollination is usually most 

 potent between styles and stamens of the same length, 

 which necessarily belong to different flowers, and less 

 potent or wholly impotent or even positively injurious 

 between styles and stamens of unequal length. The 

 pollination of the first kind has been described as 



Fig. loi.— Dimorphic or Heterostylic Flower 



LEGiiiMATE, and of the second kind as illegitimate. 

 Similarly there are trimorphic flowers. 



Fifth, CLEiSTOGAMOus FLOWERS. There are some 

 homogamous flowers which never open, and have 

 therefore no chance of getting foreign pollen. They ■ 

 are therefore necessarily self-pollinated. These are 

 known as cleistogamous. There are also pseudo- 

 CLEiSTOGAMOUS flowers, which open for a short time 

 and then close permanently. These are usually self- 

 pollinated, though cross-pollination is not excluded. 



Sixth. There are, however, many open homo- 

 gamous flowers in which self-pollination usually takes 

 place, though cross-pollination is not excluded. 



The results of investigations on pollination may be 

 summarized in the words of Hildebrand : "There are 



