IRbofcora 



JOURNAL OF 



\ THE NEW ENGLAND BOTANICAL CLUB 



Vol. 18. June, 1916. No. 210. 



A REVISION OF THE NORTH AMERICAN SPECIES OF 

 POTAMOGETON OF THE SECTION COLEOPHYLLL 



Harold St. John. 



The genus Potamogeton has been the object of much study in Europe 

 and in America, and consequently boasts an abundant literature. 

 Within the last twenty-five years five authors have published mono- 

 graphic treatments l of it, all of which are useful to the students of the 

 North American Potamogetons because of the wide dispersal of many of 

 the species. P. pedinatus, for instance, one of the species considered 

 in this article, is the most widespread of the genus and, as Bennett 

 points out, 2 is found in all of the six zoological regions of the world 

 defined by Wallace: the Palearctic, the Nearctic, the Neotropical, the 

 Ethiopian, the Oriental, and the Australian. 



In the introduction to his monograph Morong remarks, " so protean 

 are their forms, so eccentric their action, constantly changing under 

 changed conditions of season and water, that I put forth this treatise 

 with great diffidence, and feel that the subject is very far from being 

 exhausted." Very similar are my feelings concerning this fascinating, 

 difficult genus, but in an attempt to solve some of the imperfectly 

 understood complexes I have given a detailed study to Potamogeton 



i Morong, Naiadaceae of N. Am., Mem. Torr. Bot. Club, iii. no. 2 (1893). 



Fryer, Potamogetons of the British Isles (1898-1915). 



Fischer, Dio bayerischen Potamogetonen und Zanichellien, Ber. Bayer. Bot. Ges. xi. 20-162 

 (1907). 



Ascherson und Graebner, Pflanzenreich, iv. Fam. 11 (1907). 



Taylor, N. Amer. Flor. xvii. pt. 1, 14-27 (1909). 

 2 Bennett in Fryer 1. c, ix. 



