HOOKER ON ARCTIC PLANTS. 203 



geographical position, and its former conditions, both climatal 

 and geographical. The relations between the isothermals and 

 floras in each longitude being, therefore, special and not general, 

 I shall consider them further when defining the different Arctic 

 floras. 



The northern limits to which vegetation extends varies in every 

 longitude, and its extreme limits are still unknown ; it may, 

 indeed, reach to the pole itself. Phoenogamic plants, however, 

 are probably nowhere found far north of lat. 81°. 70 flowering 

 plants are found in Spitzbergen ; and Sabine and Ross collected 

 nine on Walden Island, towards its northern extreme, but none 

 on Ross's Islet, 15 miles further to the north. Sutherland, a very 

 careful and intelligent collector, found 23 at Melville Bay and 

 Wolstenholme and Whale Sounds, in the extreme north of Baffin's 

 Bay, lat. 76° 77° N. Parry, James Ross, Sabine, Beechey, and 

 others together found 60 species on Melville Island, and Lyall 

 50 on the islands north of Barrow Straits and Lancaster Sound. 



About 80 have been detected on the west shores of Baffin's Bay 

 and Davis's Straits, between Ponds Bay and Home Bay. To the 

 north of Eastern Asia, again, Seemann collected only 4 species on 

 Herald Island, lat. 71^° N., the northernmost point attained in 

 that longitude. On the east coast of Greenland, Scoresby and 

 Sabine found only 50 between the parallels of 70° and 75° N. ; 

 whilst 150 inhabit the west coast between the same parallels. 



The differences between the vegetations of the various polar 

 areas seem to be to a considerable extent constant up to the 

 extreme limits of vegetation in each. Thus Ranunculus glacialis 

 and Saxifraga flagellaris^ which are all but absent in West 

 Greenland,* advance to the extreme north in East Greenland and 

 Spitzbergen. Caltha palustris^ Astragalus alpinus, Oxytropis 

 Uralensis and 7iigrescens, Varrya arctica, Sievei^sia Rossii, Nar- 

 dosmia cm^ymbosa, Senecio palustris^ Deschampsia ccespitosa, 

 Saxifraga hieraciifolia and Hir cuius ^ all of which are absent in 

 West Greenland, advance to Lancaster Sound and the polar 

 American islands, a very few miles to the westward of Greenland. 



On the other hand Lychnis aljnna, Arabis alpina, Stellaria 

 cerastioides^ Pote^itilla tridenfata, Cassiopeia hypnoides, Phyllo- 

 doce taxifolia, Veronica alpina, Thymus Serpyllum, Luzula 

 spicata, and Phleum alpinum, all advance north of 70° in West 

 Greenland, but are wholly unknown in any part of Arctic 

 Eastern America or the polar islands. 



The most Arctic plants of general distribution that are found 

 far north in all the Arctic areas are the following ; all inhabit the 

 Parry Islands, or Spitzbergen, or both : — 



Ranunculus nivalis. Braya alpina. 



R. auricomus. ' Cardamine bellidifolia. 



R. pygmaeus. C. pratensis. 



Papaver nudicaule. Draba alpina. 



* Both were found by Kane's Expedition, but by no previous one. 



