254 



NAJADACEiE. 



PoTAMOGETON. 



p. 196; Cham. <£• Schlecht. in Linncea, 2. p. 217; Beck, hot. p. 385; Kunth, enum. 3. 

 p. 127. 



var. fluitans : floating leaves elliptical or elliptical-lanceolate, coriaceous, tapering at the 

 base, longer than the petiole ; submersed ones very thin, membranaceous and sessile, linear, 

 with many narrow reticulations along the midrib. — P. fluitans, Pufsh, fl. 1. p. 120 ; Ell. 

 sk. 2. p. 221 ; Bigel. fl. Bost. p. 63 ; Torr.fi. 1. p. 196, Beck, hot. p. 385. P. rufescens, 

 Hook. fl. Bor.-Am. 2. p. 172. 



Perennial. Stem varying in length according to the depth of the water. Floating leaves 

 variable in size and form, but usually from 2-3 inches long and 1-2 inches broad ; in the 

 proper P. natans, mostly obtuse at the base and often cordate ; but in the variety rather acute 

 or tapering at the base, marked with numerous parallel veins which extend from the base to 

 the apex, acute or obtuse, mostly of a firm texture and opake : submerged leaves much 

 narrower and thinner than the floating ones, sometimes altogether wanting ; the reticulations 

 along each side of the midrib elongated, particularly in the var. fluitans. Stipules conspi- 

 cuous, ovate or lanceolate, acute. Peduncles sheathed at the base by the stipules, longer or 

 shorter than the leaves, often stouter than the stem. Spike about an inch long, closely covered 

 with flowers. Sepals roundish. Fruit laterally compressed, slightly margined on the back ; 

 the longitudinal section, as in most of the species, exhibiting the appearance of the human ear 

 in miniature. 



Slow streams and ponds : frecment. Fl. July. Fr. August - September. 



The plant which is called by most of our botanists P. fluitans, I have little doubt is only 

 a variety of P. natans. It is perhaps also P. rufescens of Schreb. & Chamisso. The species 

 of this section are extremely difficult to characterize, and it is possible that most of them are 

 states of P. natans. 



2. Potamogeton HETEitoPHYLLus, Schreb. ? Various-leaved Pondioeed. 



Stem branching ; floating leaves elliptical, on long petioles, slightly coriaceous, many-nerved, 

 rather obtuse at the base ; submerged ones lanceolate, very thin, obscurely 5-nerved, without 

 linear reticulations along the midrib ; peduncles much thicker than the stem, somewhat swollen 

 upward; spikes cylindrical, dense. — Hook. fl. Bor.-Am. 2. p. 172? P. Proteus, var. 

 heterophyllus, Cham. Sf Schlecht. I. c. ? 



Stem usually slender, more or less branching. Floating leaves (sometimes wanting), 1 - if 

 inch long and 4-5 lines wide, acute, rather obtuse at the base ; the petioles about the length 

 of the lamina : submerged leaves 1-2 inches long, variable in breadth, but always more or 

 less lanceolate ; the linear reticulations along the midrib either wanting, or minute and 

 obscure. Spikes about an inch long, thick, mostly shorter than the leaves. Fruit roundish- 

 ovoid, compressed, slightly crested on the back. 



Slow streams and lakes : rather frequent, particularly in the western part of the State. 

 Fl. July. Fr. August. 



