Arctic Plants: Concluding Remarks 131 b 



With regard to the American element of the arctic flora, this is distinct 

 when we compare the corresponding one of Europe and Asia, but it is not versr 

 large. We notice, for instance, Calarnagrostis purpurascens, Salix Richardsonii, 

 Anemone Drummondii, A. parvifiora, Ranunculus Sabinii, Lesquerella, Hesperis," 

 Cardamine digitata, Parrya arctica, Parnassia Kotzehuei, Saxifraga tricuspidata, 

 Dryas integrifolia, Potentilla Vahliana, Lupinus, Hedysarum, Phlox, Erigeron 

 compositus, E. grandiflorus, etc. But considered on the whole the vegetation of 

 the north coast is, as stated in the preceding, composed of types from various 

 parts of the northern hemisphere of both Worlds. It jvill thus be seen from the 

 geographical table, that the arctic coast of this continent has 88 species in com- 

 mon with Altai and Baikal, 61 species in common with the Alps and Pyrenees, 

 39 in common with Caucasus, 44 in common with the Himalayas, and- 106 in 

 common with arctic Scandinavia. 



In other words, the migration of the glacial plants cannot be disputed, and, 

 no doubt, the present arctic flora consists to a great extent of remnants of the 

 alpine floras of the tertiary period. And these alpine floras were principally 

 those of the European Alps, Altai, and Baikal, the Rocky mountains, and per- 

 haps also Caucasus and Scandinavia. With regard to Scandinavia, Nathorst 

 calls attention to the fact that while these mountains, at least at present, have 

 but a very few endemic, alpine species, we must bear in mind that owing .to the 

 enormous extent of the Scandinavian inland ice the original Scandiha^dan 

 flora became dispersed towards east, south, and southwest, and intermingled 

 with elements frona the Alps and northern Asia. 



Consequently, when the ice receded and the Scandinavian mountains were 

 again covered with vegetation, the probability is that the post-glacial flora was 

 not the same as the original one, but evidently a commingling of types from 

 various mountaih ranges farther south. Therefore, we cannot expect that the 

 present Scandinavian mountain flora may guide us as far as to obtain some 

 idea of the pre-glacial flora of these mountains, if such had really been in existence. 



However, the question as to the alpine origin of this vegetation depends 

 upon the age of these mountains. As stated by Nathorst, the highest mountains 

 were formed during the tertiary period:- the Himalayas, the Cordilleras, the 

 Alps, the Pyrenees, Caucasus, the Rocky mountains, and perhaps even some of 

 the Spitzbergen mountains; but we do not know the age of the mountains of 

 Greenland and Scandinavia. In this way we are obliged to suppose that the 

 alpine and arctic floras, or better their nearest ancestors, in thei northern hemis- 

 phere are, to a great extent, of a relatively recent -date, in any case not older 

 than the eocene period, or even a more recent one. Nevertheless, even though 

 the Alps were formed as late as the pliocene period, the flora of these mountains 

 contains more than 400 alpine species which seemingly owe their origin to these 

 mountains, and many were perhaps not developed until after the glacial epoch. 



Knally with regard to the geographical distribution of some of the species 

 which are not circumpolar and which evidently originated in some area south 

 of the arctic regions, we have seen that the present distribution might lead to 

 the acceptance of the theory, proposed by Schouw, at least in some cases. And 

 there are cases where we cannot explain how the same species could have passed 

 from one point to the other. And even if the geographical and cKmatologic 

 changes which have occurred within recent geological times must have inter- 

 rupted or rendered discontinuous the formerly continuous range of many species, 

 there are some Cases which may well be considered exceptional. I think especially 

 of the Pyrolaceae. 



Owing to the present distribution of these in both Worlds, with some of 

 them being almost equally well represented on this continent and in Europe, 

 but being so very scantily represented in Asia, none being alpine, and only one 

 being, as I presume, of arctic origin, it seems very difiicult to locate the actual 

 centre of their distribution and development. 



