THE CONTINENTAL FLORA OF SOUTH SWEDEN 229 



Chapter II. 



Survey of the continental element in the European flora. 



Definition of the continental element. 



The continental element in the F^uropean flora is formed of such 

 species as have a great distribution in Eastern Europe, and towards 

 the West sooner or later reach their limits of distribution. 



It should be pointed out that continental species are thus distinguished solely 

 with regard to their distribution. No attention is here paid to what is from an 

 ecological standpoint a continental character or to a possible immigration from 

 a more continental district. 



Continental species may be very different with regard to their distribution in 

 Siberia. The distribution in Europe, especially the situation of the western limits, 

 however, have hardly any direct connection with the possible Siberian distribution, 

 so that may here be left aside. (Yet compare later on the » Siberian* species). 

 — Species distributed only in sub- Arctic or Arctic parts of East Europe are 

 not here included. 



Naturally the continental element does not form any sharply defined part of the 

 European flora. Through numerous transitions the continental types of distribu- 

 tion are connected with several others: the (South- and) Middle European type, 

 the South European and Central European ones etc. Above all it is difficult to 

 separate continental species from those evenly distributed in South and Middle 

 Europe. I have found it most expedient to take the word » continental* in the 

 widest possible sense. Thus below are also included species that reach their 

 western limits in Western Europe, in Norway, Denmark, North-Western Germany, 

 Belgium, France, and South-Eastern England. Common to these species is above 

 all the wide distribution in Eastern Europe. 



The continental element in the flora on the Middle European plain. 



In order to show to some extent the part played by the continental element 

 in the European flora an examination will be made into the strength of the con- 

 tinental feature in difi'erent parts of that flora region which may be styled »The 

 Middle European plain » (»Balticum» in accordance with Drude, e. g. i8go). 

 Further we shall attempt to make an examination of the sociological appearances 

 of different species within the same district. 



The Middle European plain, taken as a flora district, comprises Middle Europe 

 rom Eastern Russia in the east to the Welsh and North English mountain dis- 

 tricts in the west, and from the limit of the oak in the north to Central France 



