THE CONTINENTAL FLORA OF SOUTH SWEDEN 231 

 special districts on the Middle European plain. 



> m 111 o ti to two special districts 



Silesiii ; Brandenburg South Sweden 



I'otal 

 number 



Total 

 lumber 



% 



Total 

 number 



,,, , ,. 1 Northern 

 Westphalia p^^^^^ 



Total 

 number 



Total 

 1 number 



South-eastern 

 England 



Total ' „. 

 number '^ 



Number of conti- 

 nental species in the 

 special districts 



Total j ~ 

 number I '" 



620 

 730 



970 

 800 

 820 

 847 



725 



80 



85 



760 90 

 946 91 



7>5 

 765 

 94 5 

 970 



9« I 



85 I 

 88 I 



77 

 74 ' 



849 90 



856 1 92 



835 76 



778 80 



5S0 

 620 

 777 

 845 

 800 



849 



720 



788 

 6qo 



550 

 610 

 662 

 805 

 820 

 856 

 720 



S48 

 735 



5'5 

 605 

 647 

 778 

 S47 



835 



788 



908 



283 



230 

 135 

 187 



195 

 160 



"5 

 70 



36.6 



26.6 



16 



iS 



J7-7 



15.. 



12.2 



7-5 



4.9 



the map of the soil-types in Raniann igii,p. 561): Hooker 1884, Watson 1883 

 — Of the provinces into which W'^atson has spUt up Great Britain, those he names 

 Channel, Thames, Ouse, and Trent form the district in question. 



In the statistics all tliose species have been excluded whose occurrence is decidedly 

 dependent on the activity of man; that is to say, all casuals, all introduced and na- 

 turalized species and all species that occur only in cultivated fields, at roadsides 

 and in other waste places etc. (»aliens», »colonists» and so on). Naturally it is some- 

 times difficult to judge if a species has been introduced by man, or if it is a real 

 native, solely by means of the statements of floristic works. Hence the statistics 

 cannot claim complete exactness. Some uncertainty in the calculations is also 

 caused by the different modes of treatment of critical groups of species in diffe- 

 rent floristic works. To get the numbers of species as comparable as possible, 

 the species have in such cases been taken very collectively, or they have been 

 quite excluded. 



The statistics have been brought together in Table i, where there is also a 

 list of the number of continental species in the special districts. From this table 

 it appears in the first place that there is a probably unexpectedly great coinci- 

 dence between the floras of the special districts. In most cases the percentage 

 of species common to two special districts keeps between 70 and 90, only in six 

 cases does it sink below 60. Furthermore the comparatively great uniformity is 

 shown by the number of species common to all the districts, which has been 

 found to be about 435, forming 25% of the total number of species; it is also 

 seen from the fact that the number of species occurring only in one special dis- 

 trict is only 230 (Kazan 58, Moscow^ 13, Livonia i, West Prussia 4, Silesia 27, 



