Part 1, 1909] ZANNICHELLIACEAE 17 
5. Potamogeton diversifolius Raf. Med. Repos. II. 5: 354. 1808. 
Potamogeion hybridus Michx. Fl. Bor. Am.1:101. 1803. Not P. kybridus Thuill. 1799. 
? Polamogeton porcatum Muhl. Cat. 18. 1813. 
Potamogeton Selaceus Pursh, Fl. Am. Sept. 120. 1814. 
Potamogeton capillaceum Poir. in Lam, Encyc. Suppl. 4: 535. 1816. 
? Potamogeton Zetterstedtiit Wallr. Bot. Zeit. 1: 256. 1843. 
Potamogeton diversifolius mulli-denticulatus Morong, Mem. Torrey Club 3?: 48. 1893. 
Potamogeton diversifolius tricophyllus Morong, Mem. Torrey Club 3?: 49. 1893. 
Stem simple, or the submerged part much branched; floating leaves petioled ; blades 
coriaceous, elliptic-ovate or oblong-lanceolate, obtuse or acute at the apex, narrowed into a 
slender petiole at the acute base, 4.5-11 mm. wide, 1.1-2.4 cm. long; petioles longer or 
shorter than the leaf-blades; stipules obtuse or truncate, free from the petiole, 4-9.3 mm. 
long; submerged leaves capillary or narrowly linear, 0.4-0.9 mm. wide, sometimes up to 4 
cm. long; stipules as in the floating leaves, but mostly adnate to the petioles or leaf-bases ; 
emersed spikes cylindric, 3.5-7 mm. long, the peduncles twice as long as the spike or longer, 
and as thick as the petioles of the floating leaves; submerged spikes shorter, subglobose, 
the peduncles 4-6.5 mm. long; nutlets deeply pitted and 3-keeled, the keels often bearing 
numerous bristles or teeth ; embryo a complete spiral and coiled 1% times, the curved apex 
pointing inside the base and upward. 
TYPE LOCALITY : Carolina. 
. Ft a New Hampshire to California, south to Florida and northern Mexico. Also 
in Cuba. 
i oe Linnaea 2: $1.5, f. 17; Mem. Torrey Club 3?: #/. 55; Britt. & Brown, Ill. 
6. Potamogeton dimorphus Raf. Am. Mo. Mag. 1: 358. 1817. 
Potamogeton diversifolius Barton, Fl. Phila. Prodr. 27. 1815. Not P. adiverstfolius Raf. 
Potamogeton diverstfolius spicatus Engelm. Am. Jour. Sci. 42:102, 1844. 
Potamogeton Spirilius Tuckerm. Am. Jour. Sci. II. 6: 228. 1848. 
Poltamogeton Spirillus curvifolius Peck, Ann. Rep. N. Y. State Mus, 49: 28. 1896. 
Stem simple or much branched; floating leaves petioled; blades coriaceous, ovate- 
lanceolate or oblong-lanceolate, acute or obtuse at the apex, narrowed at the base, 1-2.5 
cm. long, 3-8 mm. wide; petioles slender, about as long as the blades, or longer; stipules 
acute, axillary and free from the petioles, 3-11 mm. long; submerged leaves capillary, 1-1.4 
mm. wide, 3-~ cm. long, sometimes recurved ; emersed spikes cylindric, up to 1 cm. long; 
peduncle 1-3 times as long as the spike; submerged spikes shorter, almost globose, sessile 
or nearly so; nutlets pitted and 3-keeled, the middle keel sometimes winged, but without 
teeth or bristles; embryo a complete spiral and coiled 1% times, the curved apex pointing 
inside the base and upward. 
TYPE LOCALITY : Pennsylvania. : . a 
DISTRIBUTION: Nova Scotia to Minnesota and California, south to Virginia and Missouri. 
ILLUSTRATIONS: Barton, Fl. N. Am. 3: p/. 84, as P. diverstfolius ; Mem. Torrey Club 3?: £1. 
56; Britt. & Brown, Ill. Fl. f. 171, both as P. Spirtilys. 
7. Potamogeton epihydrus Raf. Med. Repos. II. 5: 354. 1808. 
Potamogeton natans Michx. Fl. Bor. Am. 1: 101. 1803. Not P. natans I. 1753. 
Potamogeton Nuttallii Cham. & Schlecht. Linnaea 2: 226. 1827. 
Potamogeton Pennsylvanicus Cham. & Schlecht. Linnaea 2: 227. 1827. 
Potamogeton pumilus Wulfg.; R. & S. Syst. Veg. Mant. 3: 354. 1827, - 
Potamogeton Claytoni Tuckerm. Am. Jour. Sci. 45: 38. 1843. , 
Potamogeton Nuttallii ramosus Peck, Ann. Rep. N. Y. State ed 47: 162. 1894. 
Potamogeton Nuttallii cayugensis Wiegand, Rhodora 2: 102. 19 
Stem simple or branched; floating leaves petioled; blades elliptic-lanceolate, or rarely 
obovate, obtuse at the apex and narrowed at the acute base, 3.4-9 cm. long, 6-17 mm. wide; 
petioles 2.5-10 cm. long; stipules free from the petioles, obtuse, 1.8-2.7 cm. long ; sub- 
merged leaves sessile, the blades linear or linear-lanceolate, 5-nerved, with a cellular retic- 
wlation along the midrib, 6-14 cm. long, 2.5-4 mm. wide; spikes cylindric, 1.2-6 cm. 
long, many-flowered; nutlets deeply pitted, 3-keeled, the middle keel sharp; embryo a 
complete spiral, the curved apex pointing inside the base and upward. 
TYPE LOCALITY: Canada. ud ; : 
DisTRIBUTION : Newfoundland to British Columbia, south to North Carolina and Iowa. 
ILLUSTRATIONS: Linnaea 2: pl. 6, f.25; Mem. Torrey Club 3?: f/. 29; Britt. & Brown, Ill. 
Fl. f. 146; Engler, Pflanzenreich 41: /. Db. 
