ZANNICHELLIACEAE. 



VOL. I. 



8. Potamogeton Faxoni Morong. Faxon's 

 Pondweed. Fig. 181. 



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. varians, 2'-$' long, 8"-i2" wide, 13-17- 

 nerved, on petioles 2'-6' long ; submerged leaves 

 oblong-lanceolate, acute or sometimes obtuse, 

 3 '-5' long, 6"-i2" wide, 5-i3-nerved, often with 

 an irregular areolation on each side of the midrib, 

 borne on petioles \'-2.' in length; peduncles 

 slightly thicker than the stem, 2'-$' long; spikes 

 dense, i'-2 f long; fruit not collected. 



Little Otter Creek and Lake Champlain, Ferris- 

 burg, Vermont. 



9. Potamogeton heterophyllus Schreb. Various-leaved Pondweed. Fig. 182. 



Potamogeton heterophyllus Schreb. Spicil. Fl. 

 Lips. 21. 1771. 



Potamogeton heterophyllus var. maximus Mo- 

 rong, Mem. Torr. Club, 3: Part 2, 25. 1893. 



Potamogeton heterophyllus var. longipenduncu- 

 latus Morong, Mem. Torr. Club, 3 : Part 2, 24. 



1893. 

 Potamogeton heterophyllus graminifolms Morong. 



Mem. Torr. Club, 3: Part 2. 24. 1893. 

 Potamogeton heterophyllus myriophyllus Morong, 



Mem. Torr. Club, 3: Part 2, 24. 1893. 

 Potamogeton heterophyllus minimus Morong, 



Mem. Torr. Club, 3: Part 2, 25. 1893. 



Stems slender, compressed, much branched, 

 sometimes 12 long. Floating leaves pointed 

 at the apex, rounded or subcordate at the base, 

 8"-4' long, 4"-i4" .wide, io-i8-nerved, on pe- 

 tioles I '-4' long; submerged leaves pellucid, 

 sessile, linear or linear-lanceolate, acuminate 

 or cuspidate, rather stiff or flaccid, i'-6J' long, 

 i "-8" wide, 3-7-nerved, the uppermost often 

 petioled ; peduncles often thickened upward, 

 I '-7' long, sometimes clustered ; stipules spread- 

 ing, obtuse, 8"--i2" long; spikes 9"-!?' long; 

 fruit roundish or obliquely obovoid, i" ll 

 long, i"-i" thick, indistinctly 3-keeled; style short, obtuse, apical; apex of the embryo 

 nearly touching the base, pointing slightly inside of it. 



A very variable species, occurring in different forms throughout almost all North America ex- 

 cept the ^extreme north. Also^ in Europe. July-Sept. 



10. Potamogeton varians Morong. Spat- 

 ulate-leaved Pondweed. Fig. 183. 



Potamogeton gramineus var. ( ?) spathulaeformis 

 Robbina in A. Gray, Man. Ed. 5, 487. 1867. 



Potamogeton varians Morong ; Fryer, Jour. Bot. 27 : 

 33- 1889. 



Potamogeton spathulaeformis Morong, Mem. Torr. 

 Club, 3: Part 2, 26. 1893. 



Stems many, 'branched, 2-3 long. Floating 

 leaves obovate or elliptic, abruptly acute at the 

 apex, rather thin, 13-23-nerved, \'-2\' long, 6"-i3" 

 wide, borne on slender petioles ; submerged leaves 

 pellucid, spatulate-oblong or linear-lanceolate, 2'-4' 

 long, 3"-Q" wide, 5-i3-nerved, cuspidate or spines- 

 cent, sessile or subsessile, often reduced to phyl- 

 lodes with a very narrow blade and a long acumi- 

 nation at the 'base and apex; peduncles often 

 thickening upward, i'-2 f long; stipules obtuse, 

 faintly keeled, the apex slightly hooded ; spikes 

 large; fruit about i" long, roundish or obliquely 

 ovoid, obscurely 3-keeled, with a curved or slightly- 



