HISTORY AND AGE OF SOME ARCTIC PLANT SPECIES 217 



8. THE EURASIATIC GROUP 



This group is represented in Spitsbergen by two species only: Potentilla 

 midtifida and Comastoma tenella. Both have a very broad distribution, the 

 first one growing in Himalaya, Altai, and northeast Scandinavia, the second 

 one in the central Asiatic mountains, Siberia, Scandinavia, Iceland, reaching 

 even Greenland. They are certainly of Preglacial age. 



9. THE BERINGIAN GROUP 



This group, formed in Late Pliocene or Early Pleistocene in Beringia and 

 spreading since to east and west, is also poorly represented in the Spitsbergen 

 flora. To it belong: Arctophila fulva, which attained Scandinavia only in Late 

 Glacial time when the Bothnian Bay communicated with the Barents 

 Sea: Coptidium lapponicum, Rubus chamaemorus, and ChrysospJenium 

 tetrandrum. 



Previously I included in this group also PuccineUia phryganodes in the 

 sense of Sorensen (1953) in his recent monograph. But now I agree with 

 Love and Love (1961b), who distinguish two species, PuccineUia vilfoidea and 

 P. phryganodes. 



The geographic distribution and cytology of taxa, belonging to this complex, 

 can perhaps be explained in the following manner : the mother species of this 

 complex already existed at the end of the Pliocene somewhere in the Beringian 

 region. By geographic changes caused by glaciation and submergence the 

 Asiatic and American populations were split and gave rise to PuccineUia 

 phryganodes and P. vilfoidea. both sensu lata. During the Late Pleistocene both 

 evolved two subspecies in isolated refugia: P. phryganodes formed one 

 subspecies, now distributed in Greenland and northeastern America, and 

 another in the Beringian area. In the large ice-free area of eastern Siberia 

 PuccineUia vilfoidea formed the subspecies sibirica, occurring also in Scandi- 

 navia, whereas in Spitsbergen and Novaya Zemlya may be found ssp. vilfoidea 

 itself. This last subspecies must have been developed after the land connection 

 between Spitsbergen and Greenland was destroyed, i.e. probably after the 

 Mindel-Riss Interglacial. It must have occurred after the time when the 

 connection between the Novaya Zemlya-Spitsbergen complex was isolated 

 from the mainland, but before the isolation of Spitsbergen from Novaya 

 Zemlya was realized. 



PuccineUia vilfoidea spreads mostly by vegetative means. The relatively 

 short distance between Spitsbergen and Greenland seems to be insurpassable 

 for it; even the channel between Novaya Zemlya and the mainland is a 

 barrier to it. The occurrence of its ssp. sibirica in the Bothnian Bay indicates 

 that it was already present on the Arctic coast of Scandinavia in the early 

 Post-glacial, when the direct connection between the Bothnian Bay and the 

 Barents Sea still existed. 



