THE DICOTYLEDONES 



1855 



A somewhat special arrangement is seen in Chaerophyllnm aromaticum 

 and was described by Kerner as geitonogamy (Fig. 1760). In this species 

 each umbel contains one central and three to five marginal, hermaphrodite 

 flowers, while the intervening space is occupied by about twenty pseudo- 

 hermaphrodite ones. The hermaphrodite flowers develop first and their 



Fig. 1760. — ChaerophyJhim aromaticum. A, Hermaphrodite flowers 

 open, male flowers still closed. B, Male flowers open and drop- 

 ping pollen on the stigmas of the hermaphrodite flowers, which 

 have lost their stamens. {After Kerner ami Oliver.) 



anthers have fallen and their stigmas matured before dehiscence in the 

 pseudo-hermaphrodite flowers occurs. As the pollen is shed from these 

 latter flowers it may fall on the stigmas of the now female flowers and 

 ensure cross-pollination. 



4. Monoecism 



In this type, which is illustrated by the southern European genus 

 Echinophora, a single female flower is surrounded by a number of male ones. 

 As already mentioned the spiny stalks of these male flowers later enclose 

 the fruit. 



