THE CONTINENTAL FLORA OF SOUTH SWEDEN 369 



the extreme south of Sweden. In both cases their distribution a<>rees with that 

 of non-continental »grove» species. 



A remarkable exception is formed by Ranunculus cassubicus, the restriction of 

 whose distribution to the east of Central Sweden may possibly have its explana- 

 tion in the migrational history of the species. 



Mainly restricted to the south-east of Sweden are Anemone ranunculoides and 

 Pulmonaria obscura. I leave undecided the question whether the cause of this 

 is the ecology of the species or their migrational history. 



Thus we see that the distribution of the continental » grove » species in South 

 Sweden scarcely exhibits any of the dis.similarities which might be connected with 

 a continental-maritime formation. 



Marsh species. 



Marsh associations cannot be definitely defined: they pass without a percep- 

 tible boundary on the one side into the meadow associations and on the other 

 side into the water-plant associations. What I here mean by marsh associ- 

 ations may be held to correspond to Warming's helophyious associations. Thus 

 reed associations fall under this heading. 



A distinctive feature of marsh associations is that they have a very similar 

 composition in large areas. This, of course, stands in connection with the fact 

 that the compositional factors which are of most consequence for the species that 

 fall under this head are found under geographical conditions which vary very 

 much in other respects. 



In order to show in some detail to what extent the composition of the marsh 

 associations varies in Middle Europe I have made the following calculations. Of 

 the 174 or so marsh-plants found in the Government of Kazan, 90 % occur in 

 Silesia, 87 % in South Sweden, and 83 % in England, while of the 200 or so 

 marsh-plants of South Sweden there are 80 % in the Government of Kazan, 

 93 % in Silesia, and 91 % in England. By way of comparison it may be men- 

 tioned that of about 190 species belonging to the xerophilous grass associations 

 of the Government of Kazan, 55 % are found in Silesia, 39 % in South Sweden 

 and 25 % in England, while of the 195 or so species belonging to this category 

 in South Sweden there are 53 % in the Government of Kazan, 83 % in Silesia, 

 and 67 % in England. 



As regards the marsh associations in Middle Russia, they seem, as a rule, to 

 be more abundant in herbs than they are in Scandinavia. [See, for instance, 

 Flerov 1910, lists of species 54, 137^ 528, 608, 755, 835, 858; Savenkov 1910; 

 Kuznecov 1901; Krishevsky 191 2, pp. 322, 324 (Kherson); Naumov 1903, pp. 



