374 



Bejinett : The Halifax Potamogeton. 



from Maine ! south to Georgia, ! and from Massachusets ! west 

 to California, and Washington Ter. ! ; also in Porto Rico ! and 

 Jamaica. ! 



Roughly it may be described as P. zostevifolius (but with its 

 leaves pellucid) submerged ; and floating leaves similar to 

 P. heterophyllus Schreb. 



The oldest specimens I know of in Europe are in De Can- 

 dolle's herb, from ' Carolina, Rugel, 1841,' as * P. fiuitans Auct. 

 Am.' and in Mr. Melvill's from ' New Jersey, 1841, Kilvington ' 

 as P. heterophyllus ; though there is one that is probablv much 

 older from Rafinesque in the Delessert herbarium at Geneva as 

 P. -fiuitans, no date. 



Dr. Graebner, in his monograph of the genus in Engler's Das 

 Pflanzenreich Heft 31, 1907, places this species between P. 

 Cheesemanii Ar. Benn. and P. scelerocarpus Schumn, and the 

 nearest British species it comes to in his account is P. 

 nutans L., though there are 15 species between natans and 

 Cheesemanii. But, until the whole genus has been studied 

 anatomically in conjunction with morphological and other 

 characters, the position of many species must be held to be 

 only tentative. Whilst we must ' faggot ' our species, it must 

 be admitted they are far from being finally arranged. 



In June, Miss A. E. Vigurs kindly sent me a box of fresh 

 specimens, these were just showing the peduncules and spikes, 

 and remarks : M discovered a fresh patch of it yesterday (21st) 

 about three miles away, between Salterhebble and Elland, but 

 the water is very dirty just there, so the plants are not nice as 

 specimens. There does not seem to be nearly as much as last 

 year.'' 



Mr. Fernald has sent me a note respecting the species (see 

 below). Miss Vigurs considers the opinion he expresses 

 untenable, and I agree with her, and she remarks : * I am glad 

 that Mr. Fernald says it is only a " tentative answer," as I feel 

 sure this Pondweed is an introduction. This plant grows 

 exactly at the spot where the water from the Cotton Mill enters 

 the Canal, that is an absolute fact which I can vouch for.' 



The species being found in a canal in a manufacturing centre, 

 it seems not allowable to regard it as a native. The supposed 

 instance of introduction of P. crispus L. to N. America named by 

 Mr. Fernald, I believe cannot be upheld. Dr. Morong, in his 

 monograph had forgotten the reference of Pursh in his * Fl. 

 Amer. Scptr,' I., (1814) 121, when he says ' Canada to Virginia,' 



Naturalist, 



