PONDWEED FAMILY 71 



4 to 12 inches long, 4 to 6 lines broad, rounded at base, or tapering into a petiole 

 1 to 4 inches long; stipules 1 to 4 inches long; peduncles 2 to 3 inches long; 

 spikes 1 to 2 inches long, densely fruited; nutlet obliquely obovate, li/a to 2 

 lines long, the back 3-keeled, with the middle keel prominent. 



Ponds or slow creeks in the valleys or hills at low altitudes: Los Angeles 

 Co.; Bakersfield and Visalia ace. Bot. Death Valley; Santa Cruz; Russian 

 River; north to British Columbia and east to the Atlantic. Europe, Asia, 

 north Africa. 



Eefs. — PoTAMOGETON AMERicANUS C. & S. Ijinnaea, 2: 226 (1827); Jepson, Fl. W. Mid. 

 Cal. 2d ed. 28 (1911). P. lonchitcs Tuckerm. Am. Jour. Sci. 2d ser. 6: 226 (1848) ; Morong, 

 Mem. Torr. Club, o": 20, pi. 31 (1893). P. fluitanis of various California authors. 



6. P. heterophyllus Schreb. Stems slender, compressed, branched, 1 to 2 

 feet long; floating leaves oval to oblong-elliptical, 1 or 2 inches long, 4 to 9 

 lines wide; petioles 1 to 4 inches long; stipules 1 inch long or less; submerged 

 leaves linear-lanceolate, narrowed at base, sessile, 1 to 2 inches long, 1 to 3 lines 

 wide; spikes 1 inch long; peduncles 1 to 4 inches long; nutlet roundish, % to 

 11/2 lines long, indistinctly 3-keeled. 



Sierra Nevada at high altitudes : Volcano (formerly Whitney) Meadows, 

 ace. Bot. Death Valley; near IMono Pass ace. Bot. Cal. North to Oregon and 

 Washington and east to the Atlantic. Europe, Asia. 



Refs. — PoTAMOGETON HETEROPHYLLUS Schreb. Spicil. Fl. Lips. 21 (1771) ; Morong, Mem. 

 Torr. Club, 3=: 23 (1893). P. gramincus Wats. Bot. Cal. 2: 196 (1880), not L. 



7. P. amplif olius Tuckerm. Stems mostly simple, 2 to 4 feet long ; floating 

 leaves oblong-ovate or oval, mueronate, % to ly^ inches broad, 2 to 3 inches 

 long, the petioles of about the same length ; submerged leaves with the sides 

 folding together and assuming a falcate shape, the uppermost large, elliptical 

 or ovate, 2i/^ to 4 inches long, the lower lanceolate and often as much as 8 

 inches long and 2 inches wide (ace. Morong); spikes 1/2 to 2 inches long; 

 peduncles thickening upwards, 2 to 3 inches long; nutlet 3-keeled, the middle 

 keel prominent. 



Sierra Nevada from Red Lake on the San Joacpiin River, Congdon, northward 

 to Oregon and British Columbia and eastward to the Atlantic States. 



Refs. — POTAMOGETON AMPLiFOLiu.s Tuckerm. Am. Jour. Sci. 2d ser. 6: 225 (1848); Wats. 

 Bot. Cal. 2: 196 (1880) ; Morong, Mem. Torr. Club, 3=: 16, pi. 27 (1893). 



P. ANGUSTiPOLius B. & P. Similar to P. lueens ; upper leaves petioled, lower 

 sessile, all lanceolate or oblanceolate, undidate, crisped, shining; submerged 

 leaves serrulate at apex. — Credited to California by Taylor, N. Am. PI. 17' : 18. 



8. P. lueens L. Stem thick, branching below and bearing masses of very 

 leafy branches at summit; leaves all submerged, thin, elliptical to lanceolate 

 or oblanceolate or the uppermost oval, acute or acuminate, often undulate- 

 serrate, narrowed at base to a short petiole or sessile, 2 to 7 inches long and % 

 to 1% inches wide; stipules greenish, 1 to 2 inches long, loose and spreading, 

 sometimes very broad ; peduncles 3 to 6 inches long ; spikes 2 to 2i/4 inches long, 

 thick cylindrical; nutlet li/. lines long, nearly as broad, with 3 distinct ribs 

 on back. 



Small lakes and ponds : Penasquitas Creek, San Diego Co., ace. Parish ; San 

 Francisco; north to British Columbia and east to Nova Scotia. 



Refs. — PoTAMOGETON LUCENS L. Sp. PI. 126 (1753); Wats. Bot. Cal. 2: 196 (1880); 

 Morong, Mem. Torr. Club, 3=: 30, pi. 38 (1893); Parish, Erythca, 6: 85 (1898); Jepson, Fl. 

 W. Mid. Cal. 100 (1901). 



9. P. praelongus Wulf. Stems whitish, zigzag, 3 to 8 feet long, branching; 



