178 BRITISH PLANTS 



As a matter of fact, in this order the flowers actually 

 provide against the failure of cross-pollination. The 

 stigmas after a while, whether pollinated or not, curl 

 over their tips, and explore the withered anthers or style 

 for any stray pollen that may happen to be still clinging 

 to them, thus insuring fertilization for every ovule. 



The subject of pollination is extremely wide and varied, 

 but we have not the space to describe in detail the many 

 curious devices found in flowers to prevent self-fertiliza- 

 tion, nor to give an account of the wonderful adaptations 

 for pollination by long-tongued insects. In some cases 

 specialization has been carried to such a length that 

 fertilization is dependent upon the visit of one kind of 

 insect only, so that, in its absence,- no seed is formed. 

 The limits, then, of the plant and the insect are coter- 

 minous. In other cases the insect and the flower have 

 so adapted their habits to each other's needs that the 

 life-history of the one is not completed without the aid 

 of the other. We do not say that this is advantageous 

 to the flower. It is not. The disappearance of the insect 

 means the extermination of the flower. 



Inflorescences and Pollination. 



Flowers may be solitary, or more usually arranged in 

 groups on special stems. An inflorescence is a shoot 

 devoted entirely to the production of flowers. Most 

 solitary flowers are large and conspicuous, and insect- 

 pollinated e.g., poppy, water-lily, wood- anemone. 



I. Axis of Inflorescence Elongated : 



1. Raceme, flowers stalked. 



2. Panicle, a branched raceme. 



3. Spike, flowers sessile. 



(a) Catkin, pendulous, flowers unisexual. 

 (6) Spadix, axis fleshy, flowers unisexual and 

 surrounded by a spathe. 



4. Cyme, flowers usually stalked, axis terminating 



in a flower. 



II. Axis of Inflorescence Short : 



5. Head or capitulum, flowers sessile. 



6. Umbel, flowers stalked. 



