Fig. 44: Potamogeton gramineus: a, tip of compact flowering spike, X 4; b, keeled 

 stipules on flowering branch, X 1%; c, submersed lower part of stem, showing the 

 sterile branches with leaf variations and the young stipules clasping the stem, X %; d, 

 upper part of stem, showing submersed as well as floating leaves, X 7-,; e, achene with 

 obscure keels, X 8; f, submersed foliage, showing transitional forms, X l^f,; g, young 

 linear leaf, showing venation and tip, X 3. (From Mason, Fig. 31). 



