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XVII. Ouilines of t/ie Distribution of Arctic Plants. 



By Jos. D. Hooker, M.D., F.B.S., 8fc. 



(With a Map. Plate XXXII.) 



Read June 21st, 1860. 



I SHALL endeavour in the following pages to comply, as far as I can, with a desire 

 expressed by several distinguished Arctic voyagers, that I should draw up an account of 

 the affinities and distribution of the flowering plants of the North Polar Regions. The 

 method I have followed has been, first to ascertain the names and localities of all plants 

 which appear on good evidence to have been found north of the arctic circle in each con- 

 tinent ; then to divide the polar zone longitudinally into areas characterized by differences 

 in their vegetation ; then to trace the distribution of the arctic plants, and of their varieties 

 and very closely allied forms, into the temperate and alpine regions of both hemispheres. 

 Having tabulated these data, I have endeavoured to show how far their present distribu- 

 tion may be accounted for by slow changes of climate during and since the glacial period. 

 The arctic flora forms a circumpolar belt of 10° tp 14° latitude, north of the arctic 

 circle. There is no abrupt break or change in the vegetation anywhere along this belt, 

 except in the meridian of Bafiin's Bay, whose opposite shores present a sudden change 

 from an almost purely European flora on its east coast, to one with a large admixture of 

 American plants on its west. 



The number of flowering plants which have been collected within the arctic circle is 

 762 (Monocot. 214; Dicot. 548). In the present state of cryptogamic botany it is im- 

 possible to estimate accurately the number of flowerless plants found within the same 

 area, or to define their geographical limits ; but the following figures give the best 

 approximate idea I have obtained : — 



Filices 28 Characeae .... 2 Fungi 200? 



Lycopodiacese . . 7 Musci 250 Algae 100 



Equisetaceae . . 8 Hepaticae 80 Lichenes .... 250 



Total Cryptogams 925 



„ Phasnogams 762 



1687 



Regarded as a whole, the arctic flora is decidedly Scandinavian ; for Arctic Scandi- 

 navia, or Lapland, though a very small tract of land, contains by far the richest arctic 

 flora, amounting to three-fourths of the whole ; moreover upwards of three-fifths of the 

 species, and almost all the genera, of Arctic Asia and America are likewise Lapponian, 

 leaving far too small a percentage of other forms to admit of the Arctic Asiatic and 

 American floras being ranked as anything more than subdivisions, which I shall here call 

 districts, of one general arctic flora. 



Proceeding eastwards from Baffin's Bay, there is, first, the Greenland district, whose flora 

 VOL. XXIII. /i, 2 m 



