1856 A TEXTBOOK OF THEORETICAL BOTANY 



5. Dioecism 



This simple condition is exhibited only by two genera, Aciphylla with 

 twenty-five species in Australia and New Zealand and Arctopus with three 

 species in South Africa. 



6. Trimonoecism 



This is illustrated by Ferula, where the main umbel and its primary 

 branches all bear flowers with rudimentary stamens, but the anthers produce 

 a few viable pollen grains. The styles are fertile. Later, male flowers with 

 functional anthers and normal stamens develop in lateral umbels. 



In general, therefore, it may be said that, while cross-pollination is the 

 rule in the family, it is achieved more by the way in which the flowers 

 develop than in any specialization to particular visitors. Thanks to the 

 production of large numbers of flowers and plenty of nectar all kinds of 

 insects visit the flowers, and such flowers as the Carrot are probably visited 

 by a larger range of insect life than almost any other species. Apart from | 



its unique pollination mechanism, the genus Ferula is worthy of special 

 mention. There are some sixty species occurring in southern Europe and 

 central Asia. F. communis (Grain Fennel) only flowers after storing up 

 material for a number of years. F. narthex and F. asafoetida are the 

 source of the drug asafoetida, which is obtained by notching the roots. In 

 Persia it is used under the name of " food of the gods" as a condiment 

 and also as a stimulant. F. ruhricaulis is the source of Gum Galbanum 

 which has medicinal properties. 



