

On American Species of the Genus Potarnogeton. 355 



middle, the style apical. Exocarp thin, produced at the back and 

 forming the wing, and less so, also, at the face. Pntamen thick- 

 ish. Seed convolute-uncinate. Intermediate in size between P. 

 compressus and P. pusillus or, major, but differing in its char- 

 acters from all our described species of this section. 



Potamogeton pusillus, (L. ) : caule subcompresso ramoso; 

 foliis omnibus submersis membranaceis pallide vel demum fus- 

 cescenti-viridibus linearibus apicem versus levissime basique bre- 

 vissime attenuatis sessilibus, basi plus minus conspicue bi.landu- 

 losis. 3-5-nervibus, subobsolete venosis; stipnlis linguiformibus 

 pellucidis acutiuscuiis ; pedunculis longiusculis subcompressis 

 spicis subinterruptis vel confertis capituliformibns longioribus; 

 fructibus recentibus oblique ellipticis, stylo subapicali brevissime 

 rostratis, subtricarinatis, carina dorsali rotundato-obtusa deorsum 

 curvatiuscula, lateralibus obsoletis. lateribus convexis, facie ob- 

 tusa. P. pusillus, L. Suec , n. 153. Chamiss. in Liuncea, 2, 

 p> 170, t. iv,f. 5. Fries NoviL, p. 48. Koch. Syn , p. 677. 

 Kth. Enum., 3, p. 136. (excl. 8.) Torr. ! FL N. Y. A. Gr. 

 Man. Hot, p. 4.57. 



a major ', (Fries.): caule compresso minus ramoso; foliis lati- 

 oribus obtusiusculis subrnucronatis saspius 5-nervibus vencsis; 

 spicis plus minus cylindricis interruptis. P. pusillus, «, Cha- 

 mis. L c. Fries I. c. Koch. I. c. Kth. I. c. P. compressus, E. 

 Bot.j t. 418, e. Fr. Mert. fy Koch. FL Germ. I, p. 856, e. Koch, 

 non L. 



mosissimo; foliis angustioribus acutiuscuiis 3-nervibus subave- 



, niis ; spicis saspius abbreviatis floribusque capitatim confertis. P. 



I pusillus, y, Chamiss. I c. P. pusillus, (?, Fries I. c. Koch I c. 



I Kth. I. c. P. pusillus, Auctt. 



y. tenuissimiis, (Mert. & Koch.): caule capillaceo e tereti- 



I subcompresso ramosissimo ; foliis angustissimis acutis cuspida- 



tisque. sub-3-nervibus nervis lateralibus obsoletis, aveniis; spicis 

 paucifloris. P. pusillus, (?, tenuissimus, M. <£• K. Germ. 1, 

 p. S56. P. pusillus, $, Chamiss. I. c. P. pusillus, y. Fries. I. c. 



Kth. I. c. 



Hab. Still and flowing waters: — « in ponds and lakes, rather 

 conspicuous; Cambridge; Lake Champlain ; Seneca Lake, New 

 York- and westward to Wisconsin (Mr. Lapham : hh. Sartv 11!) 



N 



-> in ponds, stagnant parts of fivers, rind in ditches, Cambridge ; 

 - ewton ; and fine in Tewksbury pond. — y Perm Van, New York, 

 {Dr. Sartwell!) I have seen but one specimen of-/, but it agrees 

 very well with the character of the European variety, which 

 differs from ,tf principally in its very slender stem, and much nar- 

 rowed leaves. The stem of this species is commonly more or 

 less distinctly compressed, bnt in p' and y it is often nearly or quite 

 terete ; much branched, especially in P and ; ; 1-2 feet long. 



