42 THE EVOLUTION OF PLANTS 



for crossing, though now self -fertilised. In the 

 Bee-Orchis, for example, this is obvious; the 

 flower has all the beautiful and elaborate arrange- 

 ments which in other related Orchids ensure 

 crossing, but the stalks of the pollen masses 

 are long and weak, so that they dangle down 

 and are blown by the wind against the stigma 

 of the same flower. 



Popular language, in its use of the word 

 "flower," has grasped what is really essential 

 to that type of flower which is prevalent in 

 the existing Flora and has been prevalent for 

 long ages before, as the geological record shows. 

 It is probable that the close relation to insect- 

 life has been the chief condition determining the 

 evolution of Angiosperms and giving them their 

 supremacy among living vegetation. 



The higher families of insects, which are 

 chiefly concerned in the fertilisation of flowers, 

 appeared during the Secondary period. The 

 Bees and Wasps (Hymenoptera) do not appear, 

 so far as we know, before the Upper Oolite; the 

 earliest of the Lepidoptera (Butterflies and Moths) 

 are of about the same age. Thus both these 

 groups, according to our present knowledge, 

 appeared only a little before the true Flowering 

 Plants. The insects of the Carboniferous age 

 were chiefly Cockroaches and Dragon-flies (see fig. 

 12, p. 105). The latter reached an enormous 



