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INTRODUCTION 



5. Social Flowers with completely concealed Nectar (S). 



. Nectar is here concealed as in the preceding class, but the flowers are united 

 into heads, so that they are not only rendered strikingly conspicuous, but there 

 is also a possibility of several flowers being simultaneously pollinated. To this 



1 



2 



Fig. 23. Flowers 0/ Group CH. (i) Rubus saxatilis L. (in outline). (2) Vaccinium Vitis- 

 Idaea L. (in outline). (3) Polemonium caeruleum L. 



group belong Compositae (except the anemophilous genus Artemisia). Here also 

 are included species of the genera Knautia, Scabiosa, Succisa, and Armeria. 



Fig. 24. Social Flowers, (i) Chrysanthemum alpinum Z^. (2) Gnaphalium 



Leontopodium Scop. 



Social flowers fall into two sharply demarcated oecological groups : whites and 

 yellows on the one hand, where the insect visitors are akin to those of flowers with 

 partly concealed nectar (which are almost always of these colours), and reds, blues. 



