FIELD BOOK OF PONDS AND STREAMS 



their fruits are green burs of closely packed nutlets and all 

 grow in marshy pond borders or shallows 



Fig. 6i. — i, Giant bur-reed, Sparganium eury- 

 carpiim; 2, branching bur-reed, Spargaiiium ameri- 

 canum. 



72 



