PONDWEED FAMILY 



S7 



9. Potamogeton americanus Cham. & Sch. 

 Long-leaved Pondweed. Fig. 18L 



Potamogeton americanus Cham. & Sch. Linnaea 2: 226. 1827. 

 Potamogeton lonchites Tuckerm. Am. Journ. Sci. II. 6: 226. 



1848. 



Stem terete, mtich-branched. 1-2 m. long. Flonting 

 leaves elliptic, 2-12 cm. long, 5-35 mm. wide, acute at 

 apex, rounded or rarely acutish at base, coriaceous, 

 17-27-nerved ; petioles 4-15 cm. long, about as thick as 

 the peduncles ; submerged leaves petioled, linear-lanceo- 

 n late, 10-30 cm. long, as wide or nearly as wide as the 

 floating leaves, 7-nerved, thin and pellucid, sometimes 

 tinged with red ; stipules 2-10 cm. long ; spikes cylindric, 

 2-6 cm. long, many-flowered ; peduncles as long as or 

 much longer than the spike, thickening upward ; nutlets 

 smooth, 3-keeled, the middle keel prominent, sometimes 

 slightly winged ; embryo a complete spiral, the curved 

 apex pointing just inside the base. 



Mainly in the Austral Zones; Vermont and Washington, to 

 the West Indies, Mexico, and southern California. Also in 

 Europe and Asia. Type locality: Carolina. 



10. Potamoseton lucens L. 



Shining Pondweed. 



Fig. 182. 



Potamogeton lucens L. Sp. PI. 126. 1753. 



Potamogeton proteus lucens Cham. & Schl. Linnaea 2: 197. 

 1827. 



Stems usually much-branched, thick. Leaves all 

 submerged, petioled or sometimes sessile, lanceolate, 

 elliptic or the uppermost oval, 6-16 cm. long, 2-4.5 cm. 

 wide, acute or acuminate and cuspidate at apex, rarely 

 rounded, rounded or attenuate at base ; petioles 

 0.5-2 cm. long, often winged above the middle ; 

 stipules, axillary and free from the petioles, 2-7 cm. 

 long, obtuse, 2-keeled ; spikes 4.5-6 cm. long, many- 

 flowered ; peduncles as thick or thicker than the 

 stems, 6-14 cm. long; nutlets with a groove running 

 inward from the base, thus apparently pitted ; in- 

 conspicuously keeled ; style scarcely 1 mm. long ; 

 embryo a complete spiral. 



Widely distributed over the northern hemisphere; on the 

 Pacific Coast extending from British Columbia to southern 

 California. Most common in the valleys and foothills of 

 California. Type locality: Europe. 



11. Potamogeton crispus L. 



Curled-leaved Pondweed. Fig. 183. 



Potamogeton crispus L. Sp. PL 126. 1753. 



Stems branching, compressed. Leaves all submerged, 

 linear-oblong to oblong-lanceolate, 2-5 cm. long, 5-15 

 mm. wide, sessile or semi-ample.xicaul, obtuse at apex, 

 crisped and serrulate, the midrib prominent with 2 fine 

 lateral nerves ; stipules scarious, fugacious ; propagating 

 buds prominent in the axils of decayed lea\es and at 

 the ends of branches; spikes cylindric, 12-18 mm. long; 

 peduncles as thick or thicker than the stems, often 

 recurved in fruit ; fruit ovoid, 3-keeled, the middle keel 

 with a spur-like projection near the base; style about 

 2 mm. long, nearly as long as the body of the fruit ; 

 embryo an incomplete spiral, its straight ape.x pointing 

 directh' toward the base. 



Santa Ana River, near Corona, southern California; also in 

 the Atlantic States, and Europe. Type locality: Europe. 



