THE STRUCTURE OF FLOWERS, 57 



should be compared with the usual form (Fig. 

 15, II.). 



Moreover, the fifth or posterior stamen is restored 

 in these flowers, being usually wanting in all such 

 irregular flowers, as of Labiates. 



Degradations. — As a sixth condition, it must be 

 observed that in a large number of plants some or 

 more of the floral whorls are wanting. 



In Strutliiola and Pro'teay for example, there is no 

 corolla, only a calyx (white, green, or of some other 

 colour), stamens, and pistil. In others, even the calyx 

 is suppressed, as in Euphorbias, in which, indeed, one 

 stamen only represents a male flow^er. These degrada- 

 tions are regarded in most cases as indicative of their 

 having descended from plants which possessed both 

 calyx and corolla ; but these whorls have been lost in 

 their evolutionary history. 



A few incomplete flowers are thought to be possible 

 descendants of primitive types, representing the earliest 

 stages, when Nature had not yet contrived to make 

 either a corolla or calyx. Such, e.g., is the wax plant 

 {Myri'ca), of which there are eight species in South 

 Africa. Casicari'na, the " Beefwoods " of Australia, is 

 perhaps another ; and the willows and poplars of 

 England are descendants of some very early types ; but 

 the majority of incomplete flowers are undoubtedly 

 degradations from more complete flowers. 



Form. — In endeavouring to speculate as to how and 



