



On American Species of the Genus Potamogeton. 349 



Potamogeton amplifolius, Tuckerm. This species, indicated 

 in the previous number of this Journal already referred to, oc- 

 curs very abundantly in Lake George, and in Seneca Lake, New- 

 York, in a wholly submersed state, growing in deep water, when 

 its length, its large leaves, and its finally much elongated pe- 

 duncles make it perhaps more striking than any other of our Po- 

 tamogetons. Between this, which is probably to be considered 

 the more perfect, if not the typical state, and that which I have 

 found most common in New England, and described as above, 

 in which the habit of the plant is altered by the emergence 

 of its apex, and the consequent production of floating coriaceous 

 leaves, there is another, in some respects intermediate form, 

 proper apparently to shallow pools, which demands separate no- 

 tice. The stem in this last is much abbreviated, and the approx- 

 imated leaves, either all submembranaceous, or the upper ones 

 coriaceous, are shorter, firmer, and more oval. I gathered my 

 specimens near the Niagara river, on the Canada side, and a sim- 

 ilar plant, sent from Kentucky by Dr. Short, is in Prof. Torrey's 

 herbarium. It is probable that the three states thus indicated, 

 that peculiar to deep water, and wholly submersed (forma homo- 

 phylla, Fries.), that with floating leaves differing from the sub- 

 mersed ones, in shallower water (forma he/erophylta, Fi\), and 

 the third occurring where there is least water, and passing into 

 abnormal forms (forma amphibia, Fr.) are all the prominent ones 

 of the present, as of many other species. The differences be- 

 tween plants of still deep water (status lacusfris, Fr.) and those 

 of flowing water (status fluviatilis. Fr.) though often striking as 

 respects the leaves, are much more easily appreciated than the 

 above. The fruit of this species is more or less distinctly lunate, 

 the sides somewhat flattened, and the exocarp being removed the 

 style is persistent, and the back rounded-carinate ; a sunken line 

 on each side more or less defining the subobsolete, obtuse lateral 

 keels. The heterophylline state extends westward to Fort Gra- 

 tiot, (Dr. Pitcher, Herb. Torr.!) 



Potamogeton kufkscens, (Schrad.): caule simplici tereti ; 

 foliis submersis membranaceis, superioribus nunc subpetiolatis 

 reliquis sessilibus, validiusculis anguste lanceolatis basi apiceque 

 attenuatis acutiusculis multinervibus nervis 3-5 conspicuis ; na- 

 tantibus subcoriaceis planis nervis circ. 7 subtus prominulis plus 

 minus obovato-lanceolatis apice acutiusculis, in petiolum com- 

 pres-um concavo-convexum lamina breviorem attenuatis ; stip:ilis 

 hyalinis elongatis levissime nervosis acutis; pedunculis subse- 

 qnalibus plano-eonvexis elongatis; spicis eyiiiidricis rufeseenti- 

 bus; fructibus receutibus lenticulari-compressis obovatis, stylo 

 subapicali mucronatis, dorso acutiuscule subalato-carinato, lateri- 

 bus convexis utrinque declivibus, facie acutiuscula. P. rufescens, 

 Schrad. in Chamiss. Adn., p. 5, e Cham. Chamiss. in Linnaa, 



