72 NAIADACEAE 



loaves all submerged, bright green, oblong- lanceolate, undulate, "cucullate at 

 apex," sessile by a clasping base, 4 to 9 inches long, and y 2 to 1 inch wide; 

 stipules white, the uppermost obtuse, many-nerved, usually hugging the stem, 

 % to l l /2 inches long; spikes 1 to 2 inches long, borne on peduncles 4 to 10 

 inches long (or even longer), erect and straight and often numerous; nutlet 

 2 to 2y 2 lines long. 



Deep water of ponds: Sierra Co. (ace. Bot. Cal.) ; Oregon to British Colum- 

 bia and east to New Jersey and Nova Scotia. Europe. 



Refs. POTAMOGETON PRAELONGUS Wulf. Roem. Arch. 3: 331 (1805); Wats. Bot. Cal. 2: 

 197 (1880) ; Morong, Mem. Torr. Club, 3=: 32, pi. 39 (1893). 



10. P. perfoliatus L. var. richardsonii Benn. Stems straight, simple or 

 branching; leaves long-lanceolate and acute, wavy, cordate at base and clasp- 

 ing, 1 to 4 inches long ; stipules % to % inch long, many nerved, often becom- 

 ing much frayed ; spikes 8 to 11 lines long; peduncles- 1*4 inches long ; nutlet 

 1% lines long. 



Sisson (Siskiyou Co.) ace. Crosfield; Oregon to British Columbia; east to 



New Jersey and Nova Scotia. 



Refs. POTAMOGETON PERFOLIATUS L. var. RICHARDSONII Benn. Jour. Bot. 27: 25 (1889); 

 Morong, Mem. Torr. Club, 3 2 : 33 (1893). 



11 P. foliosus Raf. LEAFY PONDWEED. Stem flattened, much branched, 

 1 to 21/2 feet high ; leaves rather thickly clothing the stem, 1 to l l / 2 inches long. 

 y 2 to 1 line wide, abruptly acute ; stipules white, transparent, 6 to 9 lines long ; 

 flowers few in a head on a peduncle 2 to 6 lines long ; nutlet nearly 1 line long. 

 3-keeled on the back, the central keel with narrow rough-edged wing. 



North Fork of Kern River ace. Bot. Death Valley ; Gilroy ; San Francisco : 

 Birds Landing, Jepson; Mariposa, Congdon; Shasta Co., Baker; northward 

 into Oregon and east to the Atlantic States. Var. CALIFORNICUS Morong. Bushy 

 in its habit; stem thick. Southern California from San Bernardino to San 

 Diego; Oak Knoll, Los Angeles Co., ace. Davidson; eastern Oregon, ace. 

 Howell. Var. NIAGARENSIS Gray. Large-sized; leaves often 3 inches long or 

 more ; stipules longer than in the type. Visalia, ace. Bot. Death Valley. 

 Ontario to New England and south. 



' Befs. POTAMOGETON FOLIOSUS Eaf. Med. Eepos. 2d hex. 5: 354 (1808); Morong, Mem. 

 Torr. Club, 3 2 : 39, pi. 47 (1893); Jepson, Fl. W. Mid. Cal. 2d ed. 28 (1911). Var. CALI- 

 FORNICUS Morong, Bot. Gaz. 10: 254 (1885"), type from San Diego, Cleveland; Howell, Fl. Nw. 

 Am. 676 (1903). Var. NIAGARENSIS Gray, Man. 2d ed. 435 (1856). P. pauciflorus Pursh, Fl. 

 Am. Sept. 121 (1814); Wats. Bot. Cal. 2: 197 (1880); Jepson, Fl. W. Mid. Cal. 100 (1901). 

 P. niagarensis Tuekerm. Am. Jour. Sci. 2d ser. 7: 354 (1849) ; Wats. Bot. Cal. 2: 197 (1880). 



12. P. pusillus L. SLENDER PONDWEED. Stems filiform, branching, i/o to 

 1 foot long; leaves narrowly linear, acute, with a crater-like gland on each 

 side of the stem at base of the petiole or rarely glandless, 1 to 3 inches long, 

 y to % line wide, sessile; stipules short, obtuse, becoming setose; peduncles 

 flattened, slender, y 2 to 3 inches long ; spikes interrupted or capitate ; nutlet 

 obliquely elliptical, % to 1 line long, with a groove on each side of the rounded 

 back, or sometimes with 3 distinct keels, beaked by a short style. 



Santa Cruz ; Palo Alto ; San Francisco ; Sierra Nevada ; Sisson ; Oregon to 

 British Columbia and east to the Atlantic States, south into Mexico. Europe, 

 Asia. Var. TENUISSIMUS Mert. & Koch. Leaves setaceous. Soda Springs, 

 Tuolumne Meadows, ace. Bot. Cal. 



Eefs. POTAMOGETON PUSILLUS L. Sp. PI. 127 (1753); Wats. Bot. Cal. 2: 198 (1880); 

 Morong, Mem. Torr. Club, 3 2 : 45, pi. 53 (1893); Jepson, Fl. W. Mid: Cal. 100 (1901). Var. 

 TENUISSIMUS Mert. & Koch, Deutschl. Fl. 1: 857 (1823). 





