THE CONTINENTAL ELORA OE SOUTH SWEDEN 319 



Fig. 13. The <listribution of \'iola rupestris in ihe 



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 L'inland; 

 Erom a rich distribution in large parts of South Einland (»In Eennia austraU 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 19 13). 

 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 be sought 

 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 Einland 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. Hut the rise of the northern limit 



