20 NORTH AMERICAN FLORA [VoLuME 17 
acutish at the base; petioles as thick as or a little thinner than the peduncles, 4-18 cm. long; 
submerged leaves petiolate; blades thin and pellucid, sometimes tinged with red, linear- 
lanceolate, 10-30 cm. long, as wide or nearly as wide as the floating leaf-blades, 7-nerved, 
sometimes with intermediary secondary nerves; stipules 2-10 cm. long, acute, acuminate 
or obtuse ; spikes cylindric, 2-6 cm. long, many-flowered; peduncles thickening upward, as 
long as or much longer than the spike ; nutlets smooth, 3-keeled, the middle keel prominent 
and sometimes slightly winged; embryo a complete spiral, the curved apex pointing just 
inside the base, 
TYPE LOCALITY: Carolina. 
DISTRIBUTION : Vermont to Washington, south to Virginia, southern California, Texas, and 
Mexico ; also in Cuba, Haiti, and Jamaica. , 
ILLUSTRATIONS : Linnaea 2: fl. 6, f. 26; Mem. Torrey Club 3?: p/. 32; Britt. & Brown, Ill. Fl. 
SJ. 148 (the last two as P. lonchites). 
14. Potamogeton occidentalis Sieber, Linnaea 2: 224. 1827. 
Potamogeion fluitans Roth, Fl. Germ. 1: 72, in part. 1788. 
Stem simple or branched; floating leaves petioled; blades coriaceous, elliptic-lance- 
olate, acutely attenuate at both ends, 4-10 cm. long, 1.5-2.3 cm. wide; primary nerves 
mostly 5, but often with intermediary secondary ones; petioles as thick as the stem and up 
to 12 cm. long; submerged leaves petioled ; blades translucent, elliptic-lanceolate, 6-12 cm. 
long, as wide as or a little wider than the floating leaf-blades, acute at both ends, petioles 
0.5-4 cm. long; stipules acute or acuminate, 1.5-4 cm. long; spikes cylindric, 1-3.5 cm. 
long, many-flowered, sometimes interrupted ; peduncles as thick as the petioles or thicker, 
4-10 cm. long; nutlets smooth, 3-keeled, the middle keel often prominently winged on the 
upper half; embryo a complete spiral, the curved apex pointing inside the base. 
TYPE LOCALITY : Santo Domingo. 
DISTRIBUTION : Santo Domingo, Jamaica, Porto Rico, and Martinique. 
ILLUSTRATION : Linnaea 2: pl. 6, f. 24 
15. Potamogeton Faxoni Morong, Mem. Torrey Club 3’: 22. 1893. 
Stem simple or branched; floating leaves petioled; blades obovate or spatulate, obtuse 
or rounded at the apex and narrowed at the acute base into a slender petiole, 3.5-8 cm. 
long, 1.3-3.2 cm. wide; petioles longer or shorter than the leaf-blades; submerged leaves 
petioled; blades translucent, oblong-lanceolate, acute at both ends, 3-11 cm. long, as wide 
or nearly as wide as the floating leaf-blades; primary nerves 7, with often several sec- 
ondary and intermediate nerves; petioles slender, 1-4 cm. long; spikes cylindric, many- 
flowered, sometimes interrupted, 2.5-3.5 cm. long; peduncles thicker than the petioles, 
4-12 cm. long; fruit unknown. 
TypPE LOCALITY: In Lake Champlain, Ferrisburg, Vermont. 
DISTRIBUTION : Known only from the type locality. 
ILLUSTRATONS: Mem. Torrey Club 3?: /. 32; Britt.& Brown, Ill. Fl. f. 149. 
16. Potamogeton illinoensis Morong, Bot. Gaz.5: 50. 1880. 
Stem branched; floating leaves petiolate; blades coriaceous, thick, ovate or elliptic- 
ovate, mucronate at the apex, rounded or subcordate at the base and sometimes decur- 
rent, 8-14 cm. long, 4~8 cm. wide; petioles 6-10 cm. long, sometimes winged; submerged 
leaves petioled; blades mostly lanceolate-oblong, acute or acuminate at the apex and nar- 
rowed or sometimes decurrent at the base, 8-18 cm. long, as wide as or a little wider than the 
floating leaf-blades ; petioles winged, 1-2.8 cm. long, rarely longer; stipules 2.5-4.5 cm. 
long, obtuse, 2-keeled; spikes cylindric, miany-flowered, 2.54.8 cm. long; peduncles as 
thick as or thicker than the stem, 5~9 cm. long; nutlets smooth, 3-keeled, the middle keel 
sharper and more prominent than the smaller lateral ones; embryo a complete spiral, the 
curved apex pointing inside the base. 
TYPE LOCALITY: Oquawka, Illinois. 
DISTRIBUTION : Western Illinois and eastern Iowa. 
ILLUSTRATIONS: Mem. Torrey Club 3?: £/. 36; Britt. & Brown, Ill. Fl. f. 252. 
