Family POTAMOGETONACE4: 17 
Floating leaves pointed at the base; fruit distinctly 3- 
keeled, the middle keel often winged. 4. P. americanus. 
Floating leaves rounded or cordate at the base; fruit not 
. distinctly keeled. 5. P. heterophyllus. 
Be puiles adnate to the base of the leaves. 
Peduncles of the submerged spikes 4-6 mm. long. 
11. P. diversifolius. 
Peduncles of the submerged spikes not over 2 mm. long. 
12. P. dimorphus. 
With submerged leaves only. 
Leaves with broad blades. 
Leaves narrowed at the base, not clasping. 6. P. lucens. 
Leaves broad and clasping at the base. 7. P. perfoliatus. 
Leaves with narrow or capillary blades. 
Stipules free from the leaves. 
Stem flattened. 
Leaves 5-20 cm. long, 2-4 mm. wide. 8. P. compressus. 
Leaves 2-6 cm. long, 1 mm. or less wide. 9. P. foliosus. 
Stem filiform; leaves 7 mm. wide. 10. P. pusillus. 
Stipules adnate to the base of the leaves. 
Stem flattened; stigma broad, sessile. 14. P. interior. 
Stem filiform; stigma capitate, style evident. 
Fruit not keeled. 13. P. pectinatus. 
Fruit prominently keeled. 15. P. interruptus. 
1. Potamogeton natans L. 
In ponds and streams throughout the state. Cherry county; Halsey. 
2. Potamogeton amplifolius Tuckerm. 
In streams and ponds throughout the state. Atkinson; Cedar county; 
Grant county; Lincoln; Neligh. 
3. Potamogeton alpinus Balbis. 
Reported only from Cass county. 
4. Potamogeton americanus C & S. 
In ponds and streams throughout the state. Anselmo; Atkinson; 
Cedar county; Halsey; Minden; Neligh; Norway; Thedford. 
5. Potamogeton heterophyllus Schreb. 
In the North Loup river in Cherry county; Halsey; Kennedy. 
6. Potamogeton lucens L. 
Cherry county. 
7. Potamogeton perfoliatus L. 
Reported only from the northwestern part of the state. Atkinson; 
Cherry county; Halsey; Whitman. 
8. Potamogeton compressus L. 
In ponds or streams. Fremont; Greeley Center; Neligh. 
9. Potamogeton foliosus Raf. 
Common especially in alkaline lakes and ponds. Lincoln; Long Pine; 
Neligh; Paddock; Thedford; Valentine. 
10. Potamogeton pusillus L. 
In ponds and streams in the sand-hills. Atkinson; Cherry county; 
Swan Lake; Thedford. 
11. Potamogeton diversifolius Raf. 
_ Potamogeton hybridus Michx. 
Lincoln; Springview. 
