Fig. I. — Potamogeton praelongu-s. 



Fig- 2. — Potamogeton perfoliatus. 



, W^ 



Fig. 3. — Potamogeton foliosus. 



Fig, 4.- Potamogeton pusillus. 



PLATE XXXV. — WIDE-RANGING SPECIES OF PONDWEEDS. (From Morong.) 

 (After Biological Survey.) 



