TETRANDRIA TETRAGYNIA. Potamogeton. 
In ponds and rivers on sandy soil : New Jersey to Caro- 
lina. 2.July, Aug. v.v. Leaveslarger than any of 
the other sorts ; spike greenish brown, 
7. P. foliis alternis oppositisve lanceolato-ellipticis undulatis 
serratis, spicis paucifloris.— Willd. sp. pl. 1. p. 714. 
Icon; Fl.dan.927. Curt. lond. 5. t. 15. , 
In rivers and ponds: Canada to Virginia. 2. June, 
July. v.v. Spikes greenish red, small. 
$. P. foliosum ; foliis sessilibus angusto-linearibus planis, 
spicis capitatim subquadrifloris. 
P. gramineum. Mich. fl. amer. 1. p. 102. 
In rivers near the sea-coast of Lower Carolina. XY. 
9. P. foliis praelongo-setaceis approximatis distichis basi va- 
ginantibus, spicis terminalibus interruptis verticillatis, 
fructibus ovatis turgidis —Smith fl. brit. 1. p. 197. 
P. marinum. Mich. fl. amer. 1.p.102. 
; In ponds and slow-flowing waters: Canada to Pensylva- 
nia 2/.July. v.v. Only the spikes appear above 
water; flowers seldom, 
155. RUPPIA, Gen. 4.235. 
1. Ruppia. Willd. sp. pl. 1. p. 717. 
— leon. Engl. bot. 136. Mich. gen. 35. Fl. dan. 364. 
...Onthe mouth of most rivers in North America. Y. v.v. 
121 
crispum. 
pauciflorum. 
pectinatum. 
