114 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 



FiG- 23. Floiiters 0/ Group CH. (l) Rubus saxatilis /-- (in outline). (2) Vaccinium Vitis- 

 IdaciL Z.. (in outline). (3) Polcmonium caeruleum Z.. 



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

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



FlC. 34. Sociat Ftcujtrs. (1) Chrysanthemum alpinuin /,. (r) Gnaplialium 

 Leontopodium Scop. 



Social flowers fall into two sharply demarcated oecolagical groups : whiles and 

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

 partly concealed neclar (which are almost alwa}S of these coloiirs\ and reds, blues. 



