Fig. 45: Potamogeton tiatans: a, achene (longitudinal section), X 6; b, flower, X 4; 

 c, habit, showing the long linear submersed leaves and broadly elliptic floating leaves, 

 and the linear-lanceolate stipules, X %; d, achene, showing strong keel on the back, 

 X 6. (From Mason, Fig. 29). 



