158 



HETEROPHYLLY 



[CH. 



Fig. 104. Potamogeton fluitans, Roth. A land plant transferred for about a month 

 to distilled water with no substratum and the adventitious roots repeatedly re- 

 moved. The internodes marked / were formed during land life; b^, b., and 63 are 

 the surviving land leaves; the internodes tj and i, show some elongation as a 

 result of the changed conditions ; 6^ and fcg are floating leaves ; feg 

 the submerged type. [Esenbeck, E. (1914).] 



b^Q are leaves of 



