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 
Dicotyledons 
191 
1 :4-5 
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). 
tCochlearia sisymbrioides (Boreal ditto). 
Hesperis Pallasii (East and West America). 
Odontarrhena Fischeriana. 
Cardamine macrophylla. 
tArenaria macrocarpa (West America). 
fNardosmia glacialis (Arctic Asia only). 
Gmelini. 
t Artemisia Steveniana (Arctic Asia only). 
glomerata (West America). 
W 
laricina. 
t Rossii (Rocky Mountains). 
Cerastium maximum (West America). 
tOxytropis nigrescens (Boreal E. and W.America) 
Hedysarura Sibiricum. 
tSieversia glacialis (Boreal W. America). 
Potentilla stipularis. 
Osmothamnus fragrans. 
W 
W. 
fMonolepis 
W 
graminifolius. 
fragiformis. 
(West 
and W 
Claytonia lanceolata. 
fSedum euphorbioides (Arctic Asia only). 
Saxifraga Escholtzii (Boreal W. America). 
Saxifraga serpyllifolia (W. America). 
punctata (West America). 
W 
Tofieldia coccinea (E. and W. America). 
Fritillaria Kamtchatkensis (West America) . 
Carex concinna (West America). 
Elymus mollis (E. and W. 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 Arctic Asia 
which are not also American; which scarcely establishes a nearer relationship between 
Arctic Asia with Europe than with America. 
These 
Dianthus Seguieri 
superbus. 
Silene in flat a. 
Arenaria uliginosa. 
Phaca alpina. 
Hedysarum obscurum 
Rubus Idgeus. 
Sedum quadrifidum. 
Gaya simplex. 
Leontodon autumnalis. 
Hieracium alpinum. 
Veronica longifolia. 
■ 
Pedicularis Sceptrum. 
Pinguicula alpina. 
Polygonum Sibiricum* 
Salix Lapponum. 
nigricans. 
hastata. 
