56 SOUTH AFRICAN FLOWERING PLANTS. 



which swells into a honey-secreting body, as of the 

 Umbellifers.^ 



Regularity and Irregularity. — The fifth and very 

 important point, referred to under Insect-pollination, to 

 note, is that while all flowers are supposed to have 

 been at first recfular — that is, the parts of each whorl 

 were exactly alike — many flowers 

 are now irregular, in having the 

 parts of one or more whorl of 

 different forms. Thus, a flower of 

 Gera'nmm or Ox'alis is perfectly 

 regular, but that of Pelargo'nivm 

 (all these being of the same family) 

 is irregular, since the petals are not 

 all of the same size and shape. 

 Similarly, the corolla of Diivcrnui'a 

 (Fig. 13), Lobelia (Fig. 14), and 

 Leono'tis are highly irregular, having 

 a sort of " hood " behind and a 

 " lip " in front. That the ancestors 

 of irregular flowers had regular 

 corollas is to be inferred from the 

 fact that flowers of these plants are sometimes pro- 

 duced with a trumpet-shaped corolla, ha^'ing a limb 

 of five equal-sized lobes, thus being perfectly regular. 

 Thus Fig. 25 is a regular flower of a Sal' via, which 



Fig. '25. — Sal'via, with 

 regular calyx and corolla. 



* Observe the two oval bodies below the two styles in the middle 

 of the flower of Bu'bon. 



