676 NAIADACE: POTAMOGETON 
sometimes 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 1144-4 inches long: spike cylindric, about % 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. foliosus Raf. Med. Rep. (m) v, 354. Stems flattened, much bran- 
ched, 1-3 feet long: leaves 1-2 inches long, 4g-1 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 stout and 
bushy, strongly flattened and sometimes winged, thickly clustered: leaves 
smaller, with dilated midrib and frequently 5-nerved at base: uncles 
4-6 lines long, erect, clavate, flattened : spikes often ripening 12 strongly 
marked fruits. Eastern Oregon to southern California. 
P. pusillus 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 slende: flattened peduncles 4% 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. pectinatus L. Sp. 127. Stems slender, repeatedly branched, 1-3 
feet long: leaves setaceous, attenuate tothe epee. 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 
I-2 lines long, plane 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. Robbinsii 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 sey- 
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. 
Orper CV SCHEUCHZERIACEZ 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 
