366 RIKARDSTERNER 



triangle with the apex in the south-east of Norway and the base in the east 

 of Sweden. 



The distribution of P}Tola chlorantha accords tolerably well with that of the 

 pine (Plate 22). 



Although, of course, it cannot be regarded as a genuine coniferous forest plant 

 as regards mode of occurrence, mention may perhaps also be made here of 

 Ge7'aniui>i boheinicum. Its distribution in Scandinavia excellently illustrates the 

 triangular type mentioned above (Plate 12). It appears in Sweden not only in 

 places where there has been a forest fire, near charcoal-kilns and the like, but 

 also »/// ruderatisy> . The main distribution of the species would seem to lie in 

 the western part of Middle Russia, although even there it would appear to have 

 merely sporadic occurrences. (See, for instance, Paczoski 1897, '. P- i35 and 

 Petunnikov 1896, 1, p. 112). 



Grove species. 



As has already been pointed out, I bring together under the name of •f>grovesy> 

 (Swed. y>/um/ar»)c\ose mesophilous forests of broad-leaved trees casting a heavy shade. 



We find the » grove » most fully developed in Western and Central Europe, 

 where it culminates in the beech forest. Of other Central European types of 

 forest that should probably also be brought under this heading may be men- 

 tioned those described by Drude (e. g. 1896) as »Auenwalder», »Gemischte Laub- 

 holzformationen der Niederung und Hugelregion», and amongst those mentioned 

 by Hayek (1914), the following: »Gemischte Laubvvalder» (p. 89), »Auenwalder» 

 (pp. 91, 124, 146, 272), »Der herzynische Bergmischwald» (p. 91), Laubmisch- 

 walder (pp. 143, 269), and »Dic podolische Eichenwald» (p. 280). 



Outside the easterly limit of the beech in the east of Europe the »grove» be- 

 comes more infrequent and more weakly developed. The principal obstacles in 

 the way of its extension eastwards are probably the growing continentality of 

 the climate rmd the unfavourable conditions of the surface of the land. In the 

 Moscow district true »grove» vegetation appears to be encountered only on 

 shaded slopes, as in the river valleys (see, for instance, Flerov 19 10, species 

 lists 2/, 32, 65, 163, 431, 434, and 435). The bulk of the broad leaf forests 

 here consists of the above-mentioned thin birch, oak, or aspen forest. As far 

 east as the Government of Kazan, according to Korshinsky (1888), there can ^e 

 distinguished a shady ty[)e of foliferous forest. Put many of the characteristic 

 species of the Central PLuropean »grove» have reached their easterly limit to the 

 west of this. In the distribution-region thus sketched, as has been pointed out 

 above (p. 234), the »grove» has a highly varying composition. Many species that 

 are distinctive of the »grove» in PLastern and Central Europe are altogether lacking 



