264 DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 



The warming influence of the Atlantic currents being felt no further east than the Obi, 

 and the summer desiccation of the vast Asiatic continent, combine to render the climate 

 of this region one of excessive drought as well as cold ; whence it is in every way most 

 unfavourable to vegetation of all kinds. 



The total number of species hitherto recorded from this area is 233 

 /Monocotyledons 42 1 _ , .p\ 

 VDicotyledons 191 J ' / 

 The proportion of genera to species is 1:2. Of the 233 species, 217 inhabit Siberia as 

 far south as the Altai, or Japan, &c. ; 104 extend southwards to the Himalaya or moun- 

 tains of Persia ; 4 are found on the mountains of the two Indian peninsulas, and 8 on 

 those of Australia and New Zealand. All but the following 37 are European. Those 

 marked with a f are almost exclusively arctic. 



Delphinium Menziesii (West America). fNardosmia glacialis (Arctic Asia only). 



tCochlearia sisymbrioides (Boreal ditto). Gmelini. 



Hesperis Pallasii (East and West America). fArtemisia Steveniana (Arctic Asia only). 



Odontarrhena Fischeriana. glomerata (West America). 



Cardamine macrophylla. biennis (E. and W. America). 



fArenaria macrocarpa (West America). Osmothamnus fragrans. 



laricina. Pedicularis capitata (E. and W. America). 



t Rossii (Rocky Mountains). euphrasioides (E. and W. America). 



Cerastium maximum (West America). fMonolepis Asiatica (Arctic Asia only). 

 fOxytropis nigrescens (Boreal E. and AV. America). Rumex salicifolius (E. and W. America). 



Hedysarum Sibiricum. graminifolius. 



tSieversia glacialis (Boreal W. America). Salix ovalifolia (West America). 



Potentilla stipularis. Abies alba (E. and W. America.) 



fragiformis. Larix Americana (E. and W. America). 



Claytonia lanceolata. Tofieldia coccinea (E. and W. America). 



tSedum euphorbioides (Arctic Asia only). rritillaria Kamtchatkensis (West America). 



Saxifraga Escholtzii (Boi-eal W. America). Carex concinna (West America). 



Saxifraga serpyllifolia (W. America). Elymus mollis (E. and W. America). 



punctata (West America). 



Thus out of 37 non-European species, only 12 are confined to Asia, the remaining 25 

 being American. On the other hand, there are only 22 European species in Ai'ctic Asia 

 which are not also American ; which scarcely establishes a nearer relationship between 

 Arctic Asia with Europe than with America. 

 These are 



Dianthus Segiiieri. Leontodon autumnalis. 



supei'bus. Hieracium alpinum. 



Silene inflata. Veronica longifolia. 



Arenaria uliginosa. Pedicularis Sceptrum. 



Phaca alpina. Pinguicula alpina. 



Hedysarum obscurum. Polygonum Sibiricum. 



Rubus Idseus. Salix Lapponum. 



Sedum quadrifidum. nigricans. 



Gaya simplex. hastata. 



