On the Origin and Distribution of the British Flora. 11 



and doubtful species, we may well adopt Forbes's title of 

 Germanic, wliicli applies to 1059 out of 1425 British species, 

 since tlieir extension into Scotland, or their exclusive occur- 

 rence in the higher latitudes of that country, are questions 

 of secondary importance as compared with their continental 

 distribution. For the Highland type, including 120 species, 

 we may use the more general term of Arctic- Alpine, retain- 

 ing the names Asturian and Armorican for two other types or 

 subfloras.^^ With the exception of two or three waifs from 

 America, ^^ the whole British flora occurs on the Continent of 

 Europe, as we might expect, considering the reijent geological 

 date of the separation of our islands. Though, however, the 

 time which has elapsed since this separation has not been 

 sufficient for local forms of specific importance to originate, 

 it is quite possible that a minute study of what are known to 

 botanists as critical species, such as the aquatic Fiammculi, 

 the brambles, roses, hawkweeds, and willows, may disclose 

 varieties that are not only peculiar to the British Islands, but 

 to particular districts. ^^ If then we wish to investigate the 

 distribution of plants within the limits of Great Britain, we 



2*^ The revised classification will therefore be as follows : — 



Total No. of species on Watson's estimate . . 1425 



27 These are Eriocaulon septangulare, a North American species found 

 in Skye, the Hebrides, and from Antrim to Connemara ; and Spiraiithea 

 (jemmiimra, also a United States plant, which occurs in County Cork. 



28 No doubt the closer comparison of English critical forms with those 

 of the Continent will prove that many, if not all, occur in both districts ; 

 still it can hardly be doubted that the distribution-areas of segregates will 

 prove more limited than those of aggregates. This line of inqniry, which 

 requires considerable acumen, is as yet almost untouched. 



