68 



NAIADACEAE. 



6. Potamogeton alpinus Balbis. Northern Pondweed. (Fig. 147.) 



Potamogeton alpinus Balbis, Misc. Bot. 13. 1804. 

 Potamogeton rufescens Schrad. ; Cham. Adn. Fl. 



Ber. 4. 1815. 



Plant of a ruddy tinge, stems simple or branch- 

 ed, somewhat compressed. Floating leaves spat- 

 ulate or oblauceolate,obtuse,many-nerved, taper- 

 ing into petioles i'-5' long; submerged leaves 

 semi-pellucid, the lowest sessile, the uppermost 

 petioled, oblong-linear or linear-lanceolate, ob- 

 tuse or rarely acute, narrowed at the base, 3'- 

 12' long, 2"-f)" wide, 7-i7-nerved; stipules 

 broad, faintly 2-carinate, obtuse or rarely acute; 

 peduncles z'-S' long ; spikes i'-i%' long ; fruit 

 obovoid, lenticular, reddish. \%" long, i f/ thick, 

 3-keeled, the middle keel sharp, the face arched, 

 beaked by the short recurved style ; apex of 

 the embryo pointing directly to the basal end. 



In ponds. Nova Scotia to British Columbia. New 

 Jersey and California. Also in Europe. July-Aug. 



7. Potamogeton lonchites Tuckerm. Long-leaved Pondweed. (Fig. 148.) 



Potamogeton flui tans Roth, Fl. Germ, i: 72. 1788? 

 Potamogeton lonchites Tuckerm. Am. Journ. Sci. (II.) 



6: 226. 1848. 



Stem terete, much branched, 3-6 long. Float- 

 ing leaves rather thin, elliptic, pointed at both 

 ends, 2'-6 / long, 6 // -i4 // wide, many-nerved, on 

 petioles 2'-8'in length; submerged leaves pellucid, 

 4 '-13' long, 2 // -i2 // wide, rounded at the base or 

 tapering into a petiole i'-4' long; stipules i'-4' 

 long, acuminate, acute or obtuse, strongly or 

 faintly 2-carinate ; peduncles thickening upward, 

 2'-3' long; spikes cylindric. i'-2' long; fruit about 

 2" long, \"-\W thick, obliquely obovoid, the face 

 nearly straight, the back 3-keeled, the middle keel 

 rounded or often with a projecting wing under the 

 style, not impressed on the sides; embryo slightly 

 incurved, apex pointing slightly inside of the base. 



In ponds and slow streams. New Brunswick to Wash- 

 ington, south to Florida and California. July-Oct. 



Potamogeton lonchites Noveboracensis Morong, Mem. Torr. Club, 3: Part 2, 20. 1893. 

 ^Floating leaves thicker, 3'~5^' long, about 2' wide, 2o-24-nerved, abruptly pointed or obtuse at 

 ic^apex ; peduncles sometimes 4' -5' and spikes 3' long. Lakes of central New York. 



8. Potamogeton Faxoni Morong. 

 Faxon's Pondweed. (Fig. 149.) 



Potamogeton Faxoni Morong. Mem. Torr. Club, 3: 

 Part 2, 22. 1893. 



Floating leaves numerous, mostly obovate or 

 oblanceolate, blunt-pointed or obtuse at the 

 apex, narrowed at the base, often strikingly 

 like those of P. spathulaefonnis, 2'-$%' long, 

 8 // -i2 // wide, 13-17-nerved, on petioles 2'-6' 

 long; submerged leaves oblong-lanceolate, acute 

 or sometimes obtuse, 3'-$' long, 6"-i2" wide, 

 5-i3-nerved, often with an irregular areolation 

 on each side of the midrib, borne on petioles 

 l A'-2 f in length; peduncles slightly thicker than 

 the stem, 2 / -5 / long; spikes dense, i'-2' long; 

 fruit not collected. 



Little Otter Creek and Lake Chatnplain. Ferris- 

 burg, Vermont. 



