THE EVOLUTION OF THE FLOWER 121 



were it not that each group is enveloped by three 

 conspicuous bracts. These bracts are closely on 

 the lines of leaves, but are tinted in a highly 

 attractive shade of lilac. As has been indicated 

 in an earlier chapter, the Bougainvillea is well able 

 to attract the attentions of insects by means of 

 its showy appendages. A more familiar case of 

 extra floral coloration is that to be seen in the 

 Salvia horminum rubra, a common garden species. 

 This plant has adopted strange means to adver- 

 tise the presence of its small labiate flowers. 

 When in bloom the terminal leaves of each spike 

 of this Salvia are tinted in the brightest pink. 

 There is no doubt that these processes are true 

 leaves, seeing that when traversing the whole of 

 the stem it is possible to find leaves which are 

 half green and half pink. 



Further proof that the petals and sepals of 

 the flower have their origin in the foliage of the 

 plant is to be seen in the case of those species in 

 which the calyx or the corolla persists after the 

 blossom is " over/' and for a time practically 

 performs the offices of leaves. Thus with the 

 Christmas Rose the petal-like sepals which go to 

 make up what one may call the corolla, are pecu- 

 liarly tenacious in retaining their position on the 

 stem ; they do not fade away after the maturity 



