So James Small on 



accompanied by the sterilisation of the ovaries of the central 

 florets of the flower-head ; and the products were first the South 

 African marigold (Ursinia) and afterwards the ordinary marigold 

 (Calendula). 



Towards the end of the Pliooene period the wet, cold 

 conditions obtaining on the northern plains of Asia yielded a 

 belated derivative of the groundsel, the butter-bur and coltsfoot 

 type, where the flowers are developed underground in the autumn 

 and emerge only at blooming time in the spring. 



An interesting case of convergent evolution occurred quite 

 recently (Middle Pliocene, about a million years ago) in South 

 Africa. There the colonists descended from the everlasting " 

 type on the one hand and from the golden samphire type on the 

 other became so extremely alike that their progeny are classed 

 together in the same small division of a tribe of the main 

 Compositae family. 



Perhaps the most remarkable point of all is this — the original 

 groundsel type was equipped with such an adaptable constitution, 

 such an efficient dispersal mechanism and such a strong vitality 

 that it survives to the present day in all the regions to which it 

 wandered. It flourishes amongst its numerous progeny, sparsely 

 along some of the northern paths of migration, abundantly 

 wherever conditions have been sufficiently favourable to allow of 

 the development of that great number of individuals which often 

 accompanies the origin of new types. Its 2,500 species exhibit 

 every variety of herbaceous, shrubby and arboreal growth, but 

 with this amazing range of vegetative form the structure of the 

 flower-head and of the individual flowers remains constant even 

 in microscopic details. 



Such is the story of how the Groundsel wandered from its 

 Andine home all over the surface of the earth, giving rise to 

 numerous colonies, each of which developed its own peculiar 

 characteristics, so that in time the highest and largest family of 

 flowering plants, the Compositae with its 2,500 species, came 

 into being. The story, here told very briefly and imperfectly, 



