28 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



Antarctic Expedition, 11 species from the South Orkneys. It is difficult with 

 these few specimens to draw any conclusions, but it is interesting to note that all 

 except PlaCodium regale are found in the Arctic regions, and 5 are more or less 

 Alpine. 



In a paper on the Greenland lichens collected by Vanhoffen (Bibl. Bot., No. 42, 

 1897), the author of the present paper mentions that of the 286 known Greenland 

 species, 213 were found also in Germany. Of these latter 105 (i.e. 49 '4 per cent.) are 

 purely Alpine species, 11 (5'1 per cent.) prefer Alpine conditions, and 97 (45'5 per 

 cent.) are equally at home on the hills and in the plains. That is to say, 54'5 per cent. 

 are typical hill species, and none of the Greenland lichens found in Germany are 

 confined to the lowlands. The lichen vegetation of the former very closely corresponds, 

 therefore, to the German Alpine flora. 



We have not enough material to make such a complete comparison of the Antarctic 

 lichens, but I would like to give some statistics attempted with the lichens brought 

 back by H.M. discovery ships Erebus and Terror in the years 1839-43. These 

 number about 124, and 44 are apparently extra-European. But of the remaining 80 

 species, which also occur in Europe, 2'5 per cent, are typical lowland plants, 2375 per 

 cent, typical Alpine plants, 66 '25 per cent, are found on hillside and in lowland equally, 

 7'5 per cent, are exclusively Arctic, but of all the Antarctic and European species 7375 

 per cent, occur also in the Arctic regions. Even the small material before us therefore 

 admits of some interesting reflections on the great similarity between the Arctic, 

 Alpine, and Antarctic regions in their lichen vegetation. 



We can imagine the ancient polar floras having been continuous at one period, and 

 then, with the decrease in the cold of the climate, the lichens followed the retreating 

 ice and snow into the hills and the Arctic and Antarctic regions. 



We find further evidence for this when we compare the most highly developed and 

 therefore oldest lichens with the lower and therefore more recent forms, in regard to 

 their distribution in the Arctic and Alpine zones. Of the Greenland fruticulose lichens 

 5'5 per cent, alone are unknown in Germany, of the foliose forms 14 - 3 per cent, and 

 of the lower crustaceous forms as many as 35'6 per cent. But no special notice is taken 

 of those species which occur in the regions lying between Greenland and the German 

 Alps. A still more interesting comparison could be made by comparing the Antarctic 

 lichens of America with the Alpine forms of the same continent and the Arctic lichens, 

 but as yet the material at our immediate disposal makes this impossible. 



These few remarks do favour the view that a very close relationship does exist 

 between the Arctic and Antarctic lichens, which, however, must date back to the time 

 when they were still constituents of one flora. 



It will be seen from this that further collections of Antarctic lichens would be of 

 very great interest. 



