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, iy 2 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 

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

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



north Africa. 



Refs. POTAMOGETON AMERicANUS C. & S. Linnaea, 2: 226 (1827); Jepson, Fl. W. Mid. 

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

 Mem. Torr. Club, 3 2 : 20, pi. 31 (1893). P. fluitans 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 

 iy 2 lines long, indistinctly 3-keeled. 



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

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

 Washington and east to the Atlantic. Europe, Asia. 



Eefs. POTAMOGETON HETEROPHYLLUS Schreb. Spicil. Fl. Lips. 21 (1771) ; Morong, Mem. 

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



7. P. amplifolius Tuekerm. Stems mostly simple, 2 to 4 feet long ; floating 

 leaves oblong-ovate or oval, mucronate, % to l 1 /^ inches broad, 2 to 3 inches 

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

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

 or ovate, 2*X> to 4 inches long, the lower lanceolate and often as much as 8 

 inches long and 2 inches wide (ace. Morong) ; spikes % 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 Joaquin River, Congdon, northward 

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



Eefs. POTAMOGETON AMPLIFOLIUS Tuekerm. Am. Jour. Sei. 2d ser. 6: 225 (1848); Wats. 

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



P. ANGUSTIFOLIUS B. & P. Similar to P. lucens ; upper leaves petioled, lower 

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

 leaves serrulate at apex. Credited to California by Taylor, N. Am. Fl. 17 1 : 18. 



8. P. lucens 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 ^4 

 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 2y 2 inches long, 

 thick cylindrical; nutlet l 1 /^ 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. 



Eefs. POTAMOGETON LUCENS L. Sp. PL 126 (1753); Wats. Bot. Cal. 2: 196 (1880); 

 Morong, Mem. Torr. Club, 3 2 : 30, pi. 38 (1893); Parish, Erythea, 6: 85 (1898); Jepson, Fl. 

 W. Mid. Cal. 100 (1901). 



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



