230 



RIKARD STKRNER 



Tabic I. A comparison between the floras in certain 



Kazan 



Moscow 



Livonia 



West Prussia 



Silesia 



Brandenburg 



South Sweden 



Westphalia 



Northern France 



South -Eastern England 



and the uplands of Middle Germany, the Carpathians, and the South Russian 

 steppe district in the south. 



The flora region, thus delimited, may seem rather heterogeneous; several im- 

 portant forest trees, for instance, reach their boundaries within these regions, 

 such as beech, Scotch pine, spruce, hornbeam, Uimus foliacea Gilib., Acer pla- 

 tanoides etc. In order further to examine the degree of homogeneity of the flora, 

 and to find out to what extent possible lack of uniformity is to be traced back 

 to the heterogeneous distribution of continental species, a comparison will be 

 made between the floras of certain special districts in different parts of the region. 



The special districts examined and the taxonomic works used in the examina- 

 tion are as follows: 



1. The government of Kazan: Korshinsky 1898. 



2. The government of Moscow: Herder 1892, Petunnikov 1896 — 1901. 



3. Livonia (with Polish Livonia): Lehmann 1895 and 1897. 



4. West Prussia: Ascherson und Graebner 1898 — 1899, 



5. Silesia: Fiek 1881. 



6. Brandenburg: Ascherson und Graebner 1898 — 1899. 



7. South Sweden: Lindman 1918. 



8. Westphalia: Beckhaus 1893. 



9. Northern France (the departments of Somme, Pas de Calais, Nord, Ardennes, 

 and Aisne): Acloque 1903. 



10. South-Eastern England (bounded on the west and on the north by an 

 approximate line: Dorset — Nottingham — the mouth of the Humber; compare 



