THE CONTINENTAL FLORA OF SOUTH SWEDEN 



319 



Fig. I 



3. The distribution of Viola rupestris in the 

 Scandinavian North. 

 O: uncertain occurrences. 



Fig. 14. The distribution of Ranunculus polyanthemos 

 in the Scandinavian North. 

 O: uncertain occurrences. 



rences. It agrees well with the occurrence of the species in north-eastern Finland; 

 From a rich distribution in large parts of South Finland (»In Fennia australi et 

 media plerumque satis frequenter*, Hjelt) it stretches eastwards, with isolated 

 occurrences high up in the north; it reaches the Kola Peninsula, and further 

 east it is found on the River Pinega inside the Kania Peninsula (Pohle 1913). 

 The localities consist of southerly hill slopes with calcareous soil. 



We have here an example of the not uncommon circumstance that species 

 which are southern in the western parts of the Scandinavian North have a nor- 

 thern limit that rises strongly towards the east. This has recently been pointed 

 out by Samuelsson concerning several hydrophytes that are southerly in Sweden and 

 looked upon as comparatively heat-loving and exacting as regards nutrition (Sa- 

 muelsson 1920, p. 37). Samuelsson considers that the explanation should besought 

 in the wide distribution of lakes rich in nutrition in the said districts. 



Attention must also be paid, however, to the temperature conditions, especially 

 concerning Ranunculus polyanthemos. 



The distribution of the species in question towards the north in Finland and Russia 

 is due, of course, to the occurrence of calcareous soils and »Eutrophian Lake types» 

 in these districts, for the species are in their whole distribution tied to soil or 

 water that is comparatively rich in nutrition. But the rise of the northern limit 



