The Origin of our British Flora 



Caucasus. In Eastern North America, Greenland and 

 Europe, the trees were also closely allied to one another. 



The Alps possessed already such modern flowers as 

 Campanulas, Saxifrages, Primulas, Veronicas, Androsace, 

 and Rhododendrons, and though, as is the case to-day, 

 each mountain group had a flora of its own, yet certain 

 species wandered from mountain to mountain keeping 

 to the higher summits. 2 



Even to-day in Japan and East Asia one may discover 

 in the high alpine regions a few Scotch mountain plants 

 such as Phleum alpinum, Oxyria, Sibbaldia, and the 

 common butterwort. 3 



There are instances which show how after the great 

 ice invasion the same species has been separated and 

 confined in two distinct and distant mountain systems. 

 Thus Erigeron frigidus grows in the Sierra Nevada of 

 Spain and also in South-west Persia ; Scutellaria orientalis 

 is found only in Spain and in Asia Minor ; Saponaria 

 glutinosa in Spain and in the Caucasus. This shows the 

 ruthless division of kindred by the projecting fingers of 

 the northern ice. 4 



But just as interesting are those cases in which a 

 number of little special forms of one genus belong to 

 the various mountain ranges. 



Cardamine shows this very beautifully, for there are 

 forms from the Pyrenees (i sp.), Alps (4 sp.), Apennines 

 (3 sp.), Caucasus (6 sp.), Himalayas (7 sp.), and North 

 America. Besides these our own cuckoo-flower ranges 

 all round the North Pole and through the Arctic regions, 

 whilst C. impatiens may be found anywhere from Scot- 

 land to the Pyrenees, and all the way to Japan. 



Many of these northern alpine and subalpine species 

 have even invaded the highest summits of tropical 

 Africa, such as Ruwenzori, and even Kenia and Kiliman- 

 jaro, whilst others have outliers which occur in the 



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