236 



BOTANY OF THE LIVING PLANT 



by a non-functional staminode (Fig. 183), while in others of the family it 

 may be absent. In Veronica the two anterior stamens are also abortive. 

 The two posterior petals fuse so that the corolla appears to be four-lobed ; 

 the posterior sepal, which is present in the Mullein, is represented in some 

 species of Veronica by a sepal smaller than the rest ; in other species it is 

 absent, as in Veronica chamaedrys and the most of the Rhinantheae. Thus 

 the flower, though typically pentamerous, has by stages of meiomery 



FIG. 184. 



Dissections of flowers of Lychnis dioica. I., II., VIII., the pistillate flower in 

 which the stamens are represented only by staminodes (st). III., IV., IX., the 

 pistillate flowers in which the gynoecium is represented only by a vestigium (gyn). 



become apparently tetramerous. Similar changes occur in the Plantains 

 and Teasels. 



Such examples serve to show that meiomery by abortion may affect any 

 of the series of parts, and not unfrequently more than one of them in the same 

 flower. It is probably the cause of greater divergence of detail in flowers 

 than any other factor. 



The most important cases are, however, those where one or other 

 of the essential organs may be wholly abortive. It frequently occurs 

 that flowers typically hermaphrodite may be staminate or pistillate, by 





