A GUIDE AND KEY TO AQUATIC PLANTS 71 



8. P. angustifolius Berchtold & Presi — Range same as two preced- 

 ing, but infrequent. 



9. P. gramineus L. — The range of this very variable species covers 

 all of our territory. 



10. P. illinoensis Morong — Should occur over all of our range. 



11. P. perfoliatus L. — Slow streams and ponds, various provinces, 

 over all of our territory. 



12. P. bupleuroides Fernald— Found mostly in brackish waters, 

 range extends south to Florida. 



13. P. jpectinatus L. — Characteristic of hard water streams or lakes, 

 range includes all of our territory. 



14. P. foliosus Raf. — Known from our area only in Georgia and 

 Tennessee except fpr isolated stations in the Coastal Plain of South 

 Carolina and Florida. 



15. P. berchtoldi Fieber — Very variable species, known only from 

 one or two isolated stations in our territory, probably occurs more 

 widely unrecognized. Cited as P. pusillus L. by Small. 



2. Zannichellia [Mich.] L. 



Zannichellia palustris L. Horned Pondweed — Hard waters and 

 brackish as well as fresh situations, infrequent, should range over most 

 of our area. 



3. Najas L. 



1. Seed shining and obscurely marked; style 1 mm. or 



more long. l.A'^. flexilis. 



1. Seed dull, coarsely pitted; style 0.5 mm. long or less 2. N. guadalupensis. 



1. A^. flexilis (Willd.) R. & S. — Species of Najas observed by the 

 senior author in the southeast have not been separated, but this is 

 likely the most common species. 



2. A^. guadalupensis (Spreng.) Morong — Supposed to be rare and 

 local. In addition another species, A^^. gracilis (Morong) Small, listed 

 by Small from fresh water situations in Florida, is probably more 

 properly A^. marina L. var. gracilis Morong. 



4. Ruppia L. 



R. maritima L. Widgeon-grass — Rarely occurs inland, primarily a 

 brackish water species, noted in artesian porids along the coast in 

 Georgia. 



