676 NAIADACE^E POTAMOGETON 



aometimes winged, widely branching: leaves linear: mucronate or short- 

 pointed at the apex, 2-12 inches long. 1-2 lines wide, with 3 principal nerves 

 and many fine ones : stipules scarious, finely nerved, soon perishing : pe- 

 duncles l%-4 inches long: spike cylindric, about Y z inch long, 12-15-flow- 

 ered : fruit obovoid with a broad base, about 2 lines long, 3-keeled on the 

 back, the lateral keels rather obscure, beaked with a short recurved style : 

 embryo slightly incurved. In still or running water, Oregon to New Jersey 

 and New Brunswick : also in Europe. 



P. t'olipsns Raf. Med. Rep. (11) v, 354. Stems flattened, much bran- 

 ched, 1-3 feet long: leaves 1-2 inches long, >-! line wide, acute, 3- nerved, 

 mostly glandular at base: stipules white, hyaline, obtuse to acute, 6-10 

 lines long: peduncles more or less clavate, erect, about 6 lines long : spikes 

 about 4-flowered, fruit lenticular or nearly orbicular, about 1 line in diam- 

 eter, 3-keeled on the back, the middle keel winged and sinuate-dentate, 

 the face strongly angled or arched, sharp, often with a projecting tooth at 

 base: style apical. In ponds and streams, California to Brit. Columbia, 

 and New Brunswick. 



Var. Californicus Morong Bot. Gaz. x, 254. Stems Ptout and 

 bushy, strongly flattened and sometimes winged, thickly clustered : leavea 

 smaller, with dilated midrib and frequently 5-nerved at base: peduncles 

 4-6 lines long, erect, clavate, flattened : spikes often ripening 12 strongly 

 marked fruits. Eastern Oregon to southern California. 



P. pnsillus L. Sp. 127. Stems filiform, branching, 6-24 inches long: 

 leaves narrowly linear, 1-3 inches long, rarely a line wide, often nearly se- 

 taceous, 1-3-nerved, obtuse and mucronate or acute, biglandular and sessile : 

 stipules obtuse, becoming setose: spike capitate or somewhat elongated 

 and open or interrupted, on slendei flattened peduncles % to nearly 2 inch- 

 es long: fruit obliquely ellipsoidal, about a line long, 2-grooved on the 

 back or sometimes with 3 distinct keels : apex of the embryo slightly in- 

 curved and pointing obliquely downward. In ponds, Brit. Columbia to 

 California and across the continent : also in Europe. 



-*- *- Stipules united with the sheathing base of the leaf : spikes 



interrupted. 



P. pectinatns L. Sp. 127. Stems slender, repeatedly branched, 1-3 

 feet long: leaves setaceous, attenuate to the apex, 1-nerved, 1-6 inches long, 

 often capillary and nerveless: stipules half free, 6-12 lines long, thin: 

 sheaths scarious on the margins: peduncles filiform, 2-12 inches long, 

 the flowers in verticils: fruit obliquely obovoid, with a broad thick shell. 

 1-2 lines long, plump on the sides : apex of the embryo pointing almost 

 directly toward the basal end. In ponds and brackish" or salt water, Brit. 

 Columbia to California and the Eastern States. 



P. Bobbinsii Oakes Hovey's Mag. vii, 180. Stems stout, widely bran- 

 ching, 2-4 feet long: leaves linear, 3-5 inches long, acute, finely many- 

 nerved, crowded in 2 ranks, minutely serrulate, auriculate at the point of 

 attachment with the obtuse at length setose stipules : spikes usually sev- 

 eral, on stout peduncles about an inch long, loose and more or less inter- 

 rupted, about 6 lines long : fruit oblong-obovate, nearly 2 lines long, keeled 

 with a broadish wing, acutely beaked : embryo stout, the apex pointing 

 a little inside of the basal end. In ponds and lakes, Oregon to California 

 and the Atlantic States. 



ORDER CV SCHEUCHZERIACE^ Agardh 

 Theor. Syst. PL 44. 



Marsh herbs with terete or semiterete leaves and small flow- 

 ers in terminal spikes or racemes. Perianth 4-6-parted, its 



