Part 1, 1909] ZANNICHELLIACEAE 21 
17. Potamogeton pulcher Tuckerm. Am. Jour. Sci. 
45: 38. 1843. 
Polamogeton lucens fluitans Robb. in A. Gray, Man. ed. 2. 435. 1856. 
Stem simple, rarely branched; floating leaves petioled; blades coriaceous, ovate or 
orbicular-ovate, acute or obtuse at the apex and cordate or subcordate at the base, 4-10 cm. 
long, 3-7 cm. wide; petioles as thick as the stem, 5-10 cm. long, rarely longer ; submerged 
leaves petiolate; blades pellucid or semi-coriaceous, the upper lanceolate and the lower 
spatulate-ovate and sometimes narrowed into a winged petiole, 7-20 cm. long, much nar- 
rower than the floating leaf-blades; stipules 2-keeled, acuminate or obtuse, 2.5-5 cm. long; 
spikes cylindric, 2.3-4 cm. long, densely flowered, but the fruit rarely maturing ; peduncles 
as thick as or a little thicker than the stem ; nutlets smooth, 3-keeled, the middle keel more 
prominent than the lateral ones; style at least 21mm. long; embryo a complete spiral, the 
curved apex pointing inside the base. 
TYPE LOCALITY : Medford, Massachusetts. re 
DISTRIBUTION : Massachusetts to British Columbia, south to Georgia and Arkansas. 
ILLUSTRATIONS: Engler, Pflanzenreich 41: f. 16 k-m; Mem. Torrey Club 3?: p/. 28; Britt. & 
Brown, Il. Fl. f. 145. 
18. Potamogeton polygonifolius Pourr. Mém. Acad. 
Toul. 3: 325. 1788. 
Potamogeton oblongus Viv. Ann. Bot. 17: 102. 1804. 
Stem simple or branched ; floating leaves petioled; blades coriaceous, ovate or ovate- 
elliptic, 3.5-9 cm. long, 2.5-4 cm. wide, acute or acuminate at the apex, cordate or subcor- 
date at the base; petioles as thick as the stem and as long or longer than the leaf-blades; 
submerged leaves petioled; blades translucent, 6-18 cm. long, 2.5-5 cm. wide, lanceolate, 
acute or obtuse at the apex and narrowed at the acute base; petioles slender, 4-12 cm. long; 
stipules acute, up to 4 cm. long, axillary and free from the petioles; spikes many-flowered, 
2-3.5 cm. long; peduncles 3-4 times as long as the spike and slender; nutlets smooth, 
inconspicuously 1-keeled; style scarcely 0.5 mm. long; embryo a complete spiral, the 
curved apex pointing inside the base. 
TYPE LOCALITY: Fontlaurier, France. 
DISTRIBUTION: Whitbourne, Newfoundland. : 
ILLUSTRATIONS : Linnaea 2: pl. 6, f. 19; Engler, Phanzenreich 41: f. 16 a-d, f, 
19. Potamogeton lucens L,. Sp. Pl. 126. 1753. 
Potamogeton proteus lucens Cham. & Schlecht. Linnaea 2: 197. 1827. . 
Potamogeton lucens floridanus A, Benn.; Asch. & Graebn.in Engler, Pflanzenreich 41: 161. 1907. 
Potamogeton malainus Asch, & Graebn. in Engler, Phanzenreich 411; 83, as to the Guatemalan and 
Cuban plants. 1907. 
Stem often much branched ; leaves all submerged, petioled, or sometimes sessile; blades 
often shining, translucent, lanceolate, ovate or elliptic-ovate, rounded and mucronate or 
narrowly acute at the apex and rounded or acutely attenuate at the base, 6-16 cm. long, 
2-4.5 cm. wide; margins crisped or serrulate at the apex; petioles 0.5-2 cm. long, some- 
times wanting, often winged on the upper half; stipules axillary and free from the petioles, 
2-keeled, 2-7 cm. long, obtuse; spikes 4.5-6 cm. long, maty-flowered ; peduncles as thick as 
or thicker than the stem, 6-14 cm. long; nutlets with a groove running inward from the base, 
thus apparently pitted, inconspicuously keeled ; style scarcely 1mm. long; embryo a com- 
plete spiral, the curved apex pointing inside the base. 
TYPE LOCALITY: Europe. . . . . . 
DISTRIBUTION : Massachusetts to California, south to Florida, Mexico, and Costa Rica; Cuba; 
also in Europe. . 
ILLUSTRATIONS: Linnaea 2: pl.5, f. 16a, d; Britt. & Brown, Ill. Fl. f 254, Mem. Torrey 
Club 3?: p/. 38; Fl. Dan. pd. 195; Engler, Pflanzenreich 4: f..18 a, d. 
20. Potamogeton crispus L,. Sp. Pl. 126. 1753. 
Stem mostly branched; leaves all submerged, sessile or semi-amplexicaul ; blades 
oblong-lanceolate, crisped and serrulate on the margins, obtuse or acutish at the apex, 
2-8.5 cm. long, 0.6-10 cm. wide, the midrib prominent, with 2 lateral and inconspicuous 
