388 



HUTCHINSON'S POPULAR BOTANY 



and a mid-length style ; and in the right-hand figure, six mid-length stamens, 

 .six long ones, and a short style. Now the singular fact about these flowers 

 is this : the long-styled forms are almost invariably fertilized by pollen 

 from long stamens; the mid-styled forms by pollen from mid-length 

 stamens ; and the short-styled forms by pollen from short stamens ; and 



hence, of course, 

 the flowers are 

 usually cross-pollin- 

 ated. Darwin, in- 

 deed, has shown 

 that when fertiliza- 

 tion takes place 

 under other condi- 

 tions when, for 

 instance, a long- 

 styled flower is 

 pollinated by short 

 or mid-length sta- 

 mens the seeds 

 produced are smaller 

 and less healthy. 



Hermann Miiller 

 tells us that when 

 the flower of Purple 

 Loosestrife is fully 

 expanded which, 

 however, owing to 

 the crowded nature- 

 of the spike, is not 

 often " the upper 

 petals stand vertic- 

 ally while the lower 

 project obliquely 

 forward ; and the 

 latter form, there- 

 fore, a rudimentary 

 platform for insects. 

 The irregularity in 

 position of the stamens and pistil is of more importance ; they all occupy 

 the inferior (outer) part of the tube, so that insects cannot Breach the base of 

 the flower between them, but only above them ; and their ends are bent 

 upwards, so that the under surface of the insect must come in contact 

 both with anthers and stigma. Honey is secreted by the fleshy base of 

 the flower, and surrounds the short stalk of the ovary, and fills the space 



FIG. 477. FIG (Ficus carica). 

 Longitudinal section through hypanth odium, showing the flowers in the interior. 



