Arctic Plants: Geographical Distribution 89 b 



Common to both coasts of Bering strait, and furthermore recorded from 

 Altai mountains and the Himalayas, we have thus in Festuca altaica a southern 

 type, which evidently was one of those that accompanied the arctic plants on 

 their retreat to the north during the glacial epoch. Hordeum jubatum may well 

 be considered as an introduced weed. 



Among these arctic Gramineae two species are of special interest: Poa 

 abbreviata and Calamagrostis purpurascens ; while both are undoubtedly of arctic 

 American origin, the former has also reached Spitzbergen, and the latter is not 

 so very rare in the alpine region of the Rocky mountains (Colorado) ; besides that 

 it occurs in Greenland, and on the American coast of Bering strait. With 

 reference to Poa abbreviata, Nathorst. (l.c.p. 287), mentions this in connection 

 with Glyceria angustata from Okhotsk, and Alsine Rossii from the Rocky moun- 

 tains, as being the only species which Spitzbergen has not in common with Nova 

 Zembla and Scandinavia. The occurrence of these three species in Spitzbergen 

 is very strange, inasmuch as we are entitled to believe that the flora of Spitz- 

 bergen originally came from Scandinavia and Nova Zembla in post-glacial 

 times, when these stations were connected with each other by "land." 



Calamagrostis purpurascens is one of the many American species which 

 found their way to Greenland. 



Although the large family of Cyperaceae is relatively poorly represented on 

 the arctic coast of our continent, some of the species which have been collected 

 are, nevertheless, of some interest from a geographical viewpoint. Elyna 

 Bellardii, for instance, shows a distribution of enormous extent, viz.: the arctic 

 regions of America, Greenland, Scandinavia, Russia, and Siberia; farther south 

 it is alpine in the Rocky mountains (Colorado), and it also occurs in the Alps and 

 Pyrenees, Caucasus, Turkestan, Altai, Davuria, and Iceland. It is on this 

 continent associated, to some extent, with a Cobresia, C. caricina Willd., which 

 is also arctic-alpine, and known from several of the same countries, and also from 

 the Himalayas. Of the 29 species known of these two genera, the 27 are ex- 

 clusively Asiatic, and principally natives of the Himalayas. 



Elyna is thus the only one of these which may be looked upon as an arctic, 

 circumpolar type, and it would seem very strange if the species had really 

 originated from one single centre of distribution. No doubt the Altai mountains 

 were an important centre for its distribution in Asia, and it might have reached 

 the European mountains by the way of Turkestan and Caucasus. But with 

 regard to the occurrence on this continent, and especially in the Rocky moun- 

 tains, a second centre may have been located there, from where it thus became 

 distributed farther north during the glacial epoch. Moreover, Elyna is, as 

 stated above, on this continent accompanied by Cobresia caricina, and besides 

 this, a second species, C. elachycarpa Fernald, has been detected in Maine. This 

 species, however, is by Kiikenthal referred to the genus Carex, for no other 

 reason than "Area geographica Cobresiae speciem excludere videtur." Never- 

 theless, there is a Claytonia in New Zealand, a Podophyllum in the Himalayas, a 

 Jeffersonia in Manchuria, etc. 



Of the twelve Carices collected, six are circumpolar, and we have seen 

 from the introduction the remarkable geographical range exhibited by Carex 

 incurva; nevertheless, I am most inclined to. consider these circumpolar species 

 as having originated in the north, in the polar regions; a similar northern centre 

 may also be attributed to the non-circumpolar, but exclusively arctic C. reducta, 

 C. stans, and C. compacta. 



But with reference to C. scirpoidea, this did undoubtedly originate in the 

 Rocky mountains, where it is more amply represented than anywhere else, and 

 accompanied by the variety stenochlaena, and in the Coast range, Cahfornia, by 

 the variety gigas. The fact that C. scirpoidea does also occur in Greenland, 



