174 



AfiRENCHYMA 



Other examples of adaptation to the habitat-conditions in 

 aquatics are : — restriction of the stomata to the upper surface 

 of floating leaves, development of a covering of wax on the 



Fig. 91. — Transverse section of the vascular strand of the Floating Pond- 

 weed [Potamogeton natans). C, xylem-canals ; E., endodermis ; 

 I., air-canal; P., sieve-tube. 



latter, and the aerenchyma encountered in certain marsh-plants 

 (e.g. Purple Loosestrife, Lyiliritm salicaria ; Gipsj'wort, Lycopus 

 ciirofcetts ; Hairy Willow-herb, Epilobiiim Iiirsiilitin). Aeren- 



