66 B Canadian Arctic Expedition, 1913-18 



No doubt the Altai mountains constitute a most important centre of dis- 

 tribution, and many species were developed there which succeeded in reaching 

 the northeastern corner of Asia, and from there extending to arctic America 

 and Greenland. A similar important centre was undoubtedly located in the 

 European Alps, known to be so very rich in alpine species, many being endemic 

 to these mountains. Furthermore, the Rocky mountains bear evidence of having 

 been the actual centre of an old, alpine vegetation, of which several species have 

 entered the arctic region and now constitute a large element, a truly American 

 one, of the polar flora. 



These data are consequently of great importance to the solving of the 

 problem regarding the probable location of the centres of development and 

 distribution of our arctic plants. 



However, such singular distribution of plants is more readily observed, 

 when we deal with the alpine vegetation, comparing this with the arctic. For 

 instance, in Colorado the alpine vegetation illustrates the fact at once, that it is 

 composed of six elements: circumpolar types; arctic, but not circumpolar; 

 northern, but not arctic types; northern types, endemic to North America; 

 and finally there are some southern types common to both Worlds, or endemic 

 to North America. This heterogeneous composition naturally induces us to 

 attempt some sort of tabulation of the complete geographical distribution of 

 the arctic species. But it is by no means an easy task to mark down a number 

 of species credited to the various districts in the north and south. And the 

 difficulty presents itself from the indisputable fact that many species reported 

 from the arctic have also been recorded from the south, but under other names. 

 I think especially of such species as have originated in the arctic region, but 

 were forced to migrate to the south during the glacial epoch; some of these were 

 left on the southern mountain summits, while the others returned to their 

 northern homes when the ice receded. Such species as were left on these moun- 

 tains thus represent remnants of a glacial flora, and naturally the change in the 

 climatologic conditions has, sometimes, resulted in their appearance under 

 disguised forms which not infrequently pass for different species. 



Nevertheless, if such tabulation be not absolutely correct, it will always 

 give us some idea of the distribution, in a general way, of a number of species 

 which are still recognized as identical, northern as well as southern types. 



Having thus reached to obtain a view of the geographical distribution, the 

 alpine element proves a surprisingly large representation in the north, and especi- 

 ally in the arctic region. And besides that, this same vegetation, at least a number 

 of the alpine species, show also a more or less extensive distribution through- 

 out the southern mountainous regions of both Worlds. Among these species, 

 we meet thus with some that extend to the arctic region, and others of which 

 the distribution may extend far to the north, but without reaching the arctic 

 countries. Of these the latter frequently show a vast distribution throughout 

 the northern hemisphere and, moreover, a distributign which may prove 

 exceedingly scattered. The occurrence may be so scattered, indeed, that we 

 are at a loss to appreciate how the species ever reached such stations, so remote 

 from each other. 



And as will be demonstrated in the subsequent pages, the species, which I 

 have in view, are not only such as occur on the summits of the higher mountains, 

 very remote from each other, but also such as are more or less lowland plants. 

 With respect to the origin of some of these, I have suggested the probability of 

 more than a single centre, which by no means will be in opposition to the indis- 

 putable theory relative to the migration of the plants during and after the 

 glacial period. 



Some few examples may be cited to illustrate the probability of a single 

 centre, viz.: Carex f estiva, and of evidently several: C. atrata and C. alpina. 

 Having studied several species of the genus Carex from this particular point of 

 view, we might consider for instance C. f estiva. This species is arctic, but neither 



