8 NAIADACEAE 



12. Potamogeton confervoides Reichenb. Alga -like Pondweed. 

 (Man. p. 45 ; I. V.f. 138.) In cold mountain ponds, Me. and N. H. to 

 N. J. and Pa. — Pennsylvania : Carbox, Great Lake ; Huntingdon, 

 Alexandria. 



13. Potamogeton crlspus L. Curled-leaved Pondweed. (Man. 

 p. 46 ; I. F.y. 759. ) In fresh, brackish, or even salt water, Mass. to Pa. 

 and Va. — Pennsylvania: Lancaster, Conestoga Creek ; Northampton, 

 Lehigh River and Bushkill Creek ; Huntingdon ; Allegheny ; ERIE. 



14. Potamageton zosteraefolius Schum. EEL-GR.A.SS Pondweed. 

 (Man. p. 46 ; I. F.y. 160.) In still or flowing water, N. B. to Ore., N. J. 

 and Pa. — Petinsylvania : Lancaster, Susquehanna River. 



15. Potamogeton foliosus Raf. Leafy Pondweed. (Man. p. 46; 

 I. F. y". 162.) In ponds and streams, N. B. to Br. Col., Fla. and Calif. — 

 Pennsylvania : Erie, Presque Isle. 



15a. P. foliosus Niagarensis (Tuckerm.) Morong. (Man. p. 46.) — 

 Erie, Presque Isle. 



16. Potamogeton obtusifolius Mert. & Koch. Blunt-leaved Pond- 

 weed. (Man. p. 46 ; I. F. /. /6j.) In still water, Quebec to Minn., 

 Wyo. and Pa. — Pennsylvania : Northampton, Easton ; Lancaster ; 

 Wayne. 



17. Potamogeton pusillus L. Small Pondweed. (Man. p. 47; I. 

 F.y. /68.) In ponds and slow streams, N. B. to Br. Col., Va., Tex. and 

 Calif. — Pennsylvania : Monroe ; Lancaster. 



18. Potamogeton diversifolius Raf. Rafinesque's Pondweed. 

 (Man. p. 48 ; I. F. /. /70.) In still water, Me. to Neb., Fla. and Tex. — 

 Pennsylvania : Monroe ; Northampton ; Chester ; Lancaster ; 

 York ; Franklin ; Huntingdon. 



18a. P. diversifolius multidenticulatus Morong. (Man. p. 48.) — 

 Northampton, Easton (according to Morong). 



19. Potamogeton Spirillus Tuckerm. Spiral Pondweed. (Man. 

 p. 48 ; I. F.y. ///. ) In ponds and ditches, N. S. to Minn., Va. and Neb. — 

 Pennsylvania : Bucks. 



20. Potamogeton pectinatus L. Fennel-LEaved Pondweed. (Man. 

 p. 49 ; I. F. y. //J. ) In fresh, brackish or salt water, C Breton to Br. 

 Col., Fla., Tex. and Calif. — Pennsylvania : Northampton, Black Horse 

 Tavern ; Dauphin ; Lancaster, Safe Harbor ; Erie. 



21. Potamogeton Robbinsii Oakes. Robbins' Pondweed. (Man. 

 p. 49 ; I. F. y. 775.) In ponds and lakes, N. B. to Ore., N. J., Pa. and 

 Mich. — Pennsylvania: Northampton, Lehigh River; Lancaster, 

 Susquehanna River ; Erie. 



Family 2. NAIADACEAE Lindl. Naias Family. 



1. NAIAS L. 



Leaf -blades linear : leaf-sheaths narrowly and obliquely rounded. 



I. N.flexilis. 

 Leaf-blades filiform : leaf-sheaths auricled. 2. N. gracillima. 



