Fig. 31: Potamogeton latifoUus: a, interrupted flowering spike, showing the re- 

 flexed sepaloid connectives, X 2; b, young branch, X 7-,; c, habit, X 7-,; d, achene, X 6; 

 e, achene (longitudinal section), showing tip of curved embryo directed toward base 

 of seed. X 6; f-i, sheaths and ligules, showing variation in ligule apices. X IV2; j-1, 

 leaf tips, showing variation in apices and venation, X 4. (From Mason, Fig. 15). 



