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which is very concentrated, comprising the mountains of Dovre, Sunndalen, 

 and Trollheimen (Fig. 10). Within this area, it is a very common species. 

 This picture of distribution has not changed in the time of botanical explora- 

 tions. One might infer that its delimitation is a geological one. Artemisia 

 norvegica is undoubtedly most common on easily disintegrating schist, but is 

 not merely restricted to that kind of soil. It is also commonly encountered on 

 mineral soil, poor in lime. At the eastern and southern borders of this area 

 there are schisty rocks everywhere, and accordingly a geological obstruction 







Fig. 10. The distribution o^ Artemisia norvegica in Norway. 



cannot be the delimiting agent. Though the geological situation is different at 

 the western border, there are, according to my own experience, plenty of 

 suitable localities. Nor may the altitudinal conditions, bearing in mind the 

 Post-glacial Hypsithermal period, hamper the dispersal of the species. 



If we consider the centric species one by one, we will find the same distribu- 

 tion. Among the West Arctic, bicentric species Campanula wiiflora is found 

 in the area of Jotunheimen — Trollheimen, and so are also Sagina caespitosa. 



