1^-EB. 1911.] NAKANO.—THE VEGETAT. OF LAKES AJS'D SWAMPS. 43 



Nymphsea, Brasenia, Euryale etc., mostly depends upon the 

 deposit of humus soil. 



F.g. 5. 

 Zjne of Tifp\a aigisifoUa in the eastern part of the swamp; Brasenia 

 peltata among the growth of Zizania; in the bac'v -ground we see the 

 vegetation level^) of Zizviia aqnatlca. 



This zone is wanting where the littoral part of the 

 swamp is narrow and the human agency to reclaim the 

 swamp in order to make rice-fields is strongly displayed. But 

 the zone"^ is the widest in the eastern end of the swamp, and 

 the plants, as Brasenia peltata Pursh., Euryale ferox Salisb. 

 and Trapa bispinosa Rox.,^^ are found abundantly', while they 



1) Of tliis species I liave found three types: — 



a. Type which re-emblei the Eoxburghiax type. 



p. Type which is difTerent from a, in having re:I characteristic spots on the 



leaves and also in the chnracterisfc fruits etc. 

 y. Type which is difTerent from a and a, in having a discontinuous disk at 



the base of sepals, and also in tlie characteristic fruits etc. 

 I shall give accounts on these points more precisely in another paper in near future. 



2) Yapp: On straficatlou in the vegetat'on of a marsh etc. Annals of Botany 

 Vol. 23, April 1909. 



