252 DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 



is almost exclusively Lapponian, having an extremely slight admixture of American or 

 Asiatic types : this forms the western boundary of the purely European flora. Secondly, 

 the Arctic European district, extending eastward to the Obi river, beyond the Ural range, 

 including Nova Zembla and Spitzbergen ; Greenland would also be included in it, were 

 it not for its large area and geographical position. Thirdly, the transition from the com- 

 paratively rich European district to the extremely poor Asiatic one is very gradual ; as 

 is that from the Asiatic to the richer fourth or West American district, which extends 

 from Behring's Straits to the Mackenzie River. Eifthly, the transition from the West 

 to the East American district is even less marked ; for the lapse of European and West 

 American species is trifling, and the appearance of East American ones is equally so : the 

 transition in vegetation from this district, again, to that of Greenland is, as I have stated 

 above, comparatively very abrupt. 



The general uniformity of the arctic flora, and the special differences between its sub- 

 divisions may be thus estimated : the arctic Phsenogamic flora consists of 762 species ; of 

 these, 616 are Arctic European, many of which prevail throughout the polar area, being 

 distributed in the following proportions through its different longitudes : — 



Arctic Europe . . 616: Scandinavian forms 586 ; Asiatic and American 30=1 



„ Asia .... 233 „ „ 189 „ 44 = 1 



„ W. America 364 „ „ 254 „ 110=1 



„ E.America 379 „ „ 269 „ 110 = 1 



„ Greenland . 207 ,> „ 195 „ 12 = 1 



19-57 

 4-2 

 2-3 

 2-4 



16-2 



This table places in a most striking point of view the anomalous condition of Greenland, 

 which, though so favourably situated for harbouring an Arctic American vegetation, and 

 so unfavourably for an Arctic European one, presents little trace of the botanical features 

 of the great continent to which it geographically belongs, and an almost absolute identity 

 with those of Europe. Moreover, the peculiarities of the Greenland flora are not confined 

 to these ; for a detailed examination shows that it differs from all other parts of the arctic 

 regions in wanting many extremely common Scandinavian plants which advance far north 

 in all the other polar districts, and that the general poverty of its flora in species is more 

 due to an abstraction of arctic types than to a deficiency of temperature. This is proved 

 by an examination of the temperate portion of the Greenland peninsula, which adds very 

 few plants to the entire flora, as compared with a similar area south of any other arctic 

 region; and these few are chiefly arctic plants and almost without exception Arctic 

 Scandinavian species. 



There is nothing in the physical features of the arctic regions, their oceanic or aerial 

 currents, their geographical relations, nor their temperature, which, in my opinion, at all 

 accounts for the exceptional character of the Greenland flora ; nor do I see how it can 

 be explained, except by assuming that extensive changes of climate, and of land and sea, 

 have exerted great influence, first in directing the migration of the Scandinavian species 

 over the whole polar zone, and afterwards in introducing the Asiatic and American 

 species with which the Scandinavian are so largely associated in all the arctic districts 

 except those of Europe and Greenland. It is inconceivable to me that so many Scan- 



