FEB. 1911.] NAKANO.—THE VEGETAT. OF LAKES AND SWAMPS. 



49 



Luckily the Typha- zone, as well as other littoral zones in 

 the eastern part of the swamp, is protected from the human 

 interference on account of its public hunting place of water 

 fowls. Hence here these zones have most perfectly been pre- 

 served 



lY. Geographical Distribution. 



In this chapter, an attempt will be made to show the affinity 

 between the plants of the swamp and those of other countries. 

 The total number of phanerogams found in the swamp is 47 

 species and 8 varieties. The following table will show in 

 percentage the ratio of the number of elements of various 

 countries contained in the present flora, to the total number of 

 it. The only plant endemic to the swamp is potamogeton 

 lucens var. teganumensis. 



Elements of Sachalin IS^/o 



Siberia 



Yezo 



Manchuria.... 



China proper 



Kiusiu & Loochoo. 



Formosa. ... 



British India. 



Northern North America 



Germanv. 



31^ 



4.20/0 

 6O0/0 

 67 0/0 

 67o/o 

 5I0/0 

 4^70/0 

 270/0 



Slo/o 



Evidently, this calculation is not accurate, but at large it is 

 sufficient to show the degree of their affinity. Therefore, we 

 may draw a conclusion that the flora of the swamp has the 

 nearest alliance with that of China proper or Manchuria, and 

 agrees with the floras of tropical lands, rather than with those 

 of cold regions. The former relation may be explained by 



the general assumption that the Japanese flora had originated 

 from that of Asiatic Continent. ^^ As to the latter it appears 



1) Grisebach: Die Vegetation der Erde, BJ. I. p. 489. 



Engler : Versnch einer Eutwickelnngsgescliichte der extratropischen 

 Florengebiete, p. 33. 



