200 J. O. HAGSTRÖM, CRITICAL UESEARCHES ON THE TOTAMOOETOXS. 



of some small-leaved form of P. iUinoensis by their slight size. Besides, the sterility 

 also suggests the hybrid origin of this plant. 



P. pseudolucens occurs »in lacu Fresh, Cambridge, Mass., U. S. A.» gathered 

 by T. Mokonc, 1880 (hb. Stockholm), and at N. Haven, Ct.. 1858, Eaton (hb. Christ.). 



Of P. p8eudo-2jizii, m.. which is P. gramin. illin. hicens, see under /'. 

 geaniineits/ 



P. iUinoensis Mor. X nodOSUS Tom. (P. Faxoni Moronq, A revision of the North 

 American Najadaceae etc. in Mem. Torr. bot. Club, TIT, 2, 1893, 22, t. XXX TT). 



The Potamogetons gathered by C. E. Faxon in the years 1880 and 18S2 at 

 Ferrisbergh, Vermont, U. S. A., have been judged of verv diffexently. Faxon himself 

 seems to have held them for P. rufescens ( alpinus). Ar. Bennett has thoughl 

 fchem to be P. rufescens x Nuttallii {Claytonii) (i. e. : alpinusx Nuttallii) (Journ. of Bot., 

 1890). In 1893 T. Morong has described them under the name of P. Faxoni and 

 also thought them a hybrid, but proposes the combination lonchitis X rufescens (i. e. 

 al j>inusx nodosus). In Britton & Brown, 111. Fl., 1896, this suggestion is not 

 further mentioned, in consequence whereof it is probable that Morong before lus 

 death has abandoned it as too uncertain. In 1901 Ar. Bennett (Journ. Bot.) seems 

 to have been inclined to leave the thought that /'. alpinus has been a co-agent. 

 Any closer explanation, however, is not given. P. GRAEBNER establishes P. Faxoni 

 (1907) as a proper species of the »subsectio Alpint*, but refers also to the opinion 

 of Mr Ar. Bennett (T890) though with some hesitation (>?»)• Finally Mr Au. 

 Bennett has in The Journ. of Botany, 1908, 24S, on accounl of the habitats, as- 

 serted quite a new idea of two different hybrids: one which he names P. americanus 

 (lonchites) Cham. X pensylvanicus Cham., originating from »Little Otter Creek , and 

 the other from »Lake Champlain», which he calls P. alpinus pensylvanicus or X /'. 

 Champlainii. Bennett is of the opinion that the former of those ought to main- 

 tain the name P. Faxoni. 



Before we enter upon an investigation of the plants concerned, 1 should state 

 first that I have had an opportunity to study speoimens of both the stations collect- 

 cd by Faxon himself and belonging to Morong's herbarium and by him determined 

 as P. Faxoni; and further that the Little Otter Creek is one of the rivulets flowing 

 into the Lake Champlain (emptying into the lake: Mor.). 



An examination of the fructification plainly shows that it is about a cross- 

 breed. The difficulty is to lind the two parent species of the hybrid. 



If you examine the submersed leaves you \\ill find that both the forms are 

 characterized by the margin not being smooth as in P. alpinus and NttttaUii, bul 

 Studded with small faint teet Ii. from lliat fact the sure eoneliision can be dra WD 

 that at least the one of the parents but lathcr both the parlaking species must be 



endowed with Berrulate Bubmersed leaves. Consequently the oombination alpinusx 

 Nuttallii is inconoeivable. The submersed leaves are further characterized by a nerva- 



tlOD and Struoture typical of P. nodosus and in some degree also of /'. iUinoensis 



