VEGETABLE COLONIZATION. 229 



VEGETABLE COLONIZATION OF THE BRITISH ISLES, OF 

 SHETLAND, FAROE AND ICELAND. 



BY CH. MARTINS. 



[Translated for the Smithsonian Report from the ' 'Archives des Sciences Physiques et Naturelless.' ' 



Geneva, June, 1848. ] 



Whether each plant be a native of the place where it is actually 

 reproduced, or whether, there have existed centres of creation from 

 which vegetables have been progressively distributed over the surface 

 of the earth, are questions which seem likely to divide, for some time 

 to come, the opinions of naturalists. But while those who suppose 

 the plant to have originated in the locality where we find it treat the 

 problem somewhat vaguely, those, on the contrary, who admit the 

 fact of vast vegetable migrations, similar to those of the races of man- 

 kind, and who apply to these questions the ideas furnished by geology 

 respecting the past, and by terrestrial physics and meteorology re- 

 specting the present condition of the globe, are not content to see in 

 the geographic distribution of species a fact without premises and 

 without consequences. They seek to discern therein the trace of the 

 later revolutions of our planet, and the action of those numerous and 

 varied forces which still continue to impede or promote the dissemina- 

 tion of plants. They strive to trace upon the map the march of those 

 vegetable hosts which have overrun certain countries, leaving others 

 to retain their primitive flora. Such studies date from yesterday; 

 but reflective minds will scarcely fail to presage their importance. 

 In effect, the creation of existing vegetables has followed close upon 

 the emergence of continents and islands, being in some sort the last 

 act of the geologic history of our globe. Still later, man makes his 

 appearance and tradition commences. 



Botanists have long remarked that certain islands have a flora 

 peculiar to themselves,, while others afford no plant which does not 

 equally appear on the nearest continent. The British islands are of 

 this class ; but we shall not limit our consideration to England, Scot- 

 land and Ireland, we shall attempt to follow the vegetable migration 

 through that archipelago of larger and smaller islands, which, under 

 the names of Orkneys, Shetland, Faroe, and Iceland, form the only 

 chain which connects middle Europe with northern America. 



Turning our attention first to the botanical geography of the British 

 isles, we have for our guide the ingenious labors of Mr. Hewett Wat- 

 son* and Mr. Edward Forbes. f Both have carefully explored their 



"■ Remarks on the geographical distribution of British plants in connexion with latitude, elevation, 

 and climale, 1 vol., 8vo. , 1835 ; and Cybele Britannica, vol. 1, 1847. 



fOn the connexion between the distribution of the existing fauna and flora of the 

 British isles and the geological changes which have affected their area, especially during 

 the epoch of the northern drift. — {^Memoirs of the geological survey of Great Britain, vol. 1, 

 p. 336. 



