II] GEOGRAPHICAL DISTRIBUTION 19 



us either to trace the separate branches to a common 

 origin or to recognise a convergence towards a 

 common stock. Were a botanist to find himself in 

 a forest of the Coal age he would experience great 

 difficulty in assigning some of the plants to their 

 s} stematic position : characters now regarded as 

 distinguishing features of distinct groups would be 

 met with in combination in a single individual. It 

 is by the discovery of such generalised types, which 

 serve as finger-posts pointing the way to lines of 

 evolution, that the student of pre-existing plants has 

 been able to throw light on the relative antiquity of 

 existing forms, and to trace towards a common 

 ancestry plants which now show but little indication 

 of consanguinity. 



Confining our attention to the dominant group of 

 plants in the British flora, namely the Flowering 

 Plants, we may profitably consider the question, 

 though we cannot satisfactorily answer it, — which 

 members of this group are entitled to be regarded 

 as the most ancient inhabitants ? The past history 

 of our native plants, and their geographical range, 

 not only in the British Isles but on the Continent 

 of Europe, are subjects well worthy of the attention 

 of field-botanists whose interests are apt to be 

 confined within too narrow bounds. There are 

 numerous problems relating to the composition of 

 the present vegetation of Britain which might be 



2—2 



