ZANNICHELLIACEAE 41 



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blades 4-15 cm. long, usually acute: drupelets 3.5-4 mm. long, the middle keel promi- 

 nent. [P. lonchites Tuckerm.] 



In ponds and rivers, New Brunswick to Washington, Florida and California. Also in 

 the West Indies. Summer and fall. 



8. Potamogeton angustifolius Berch. & Presl. Leaves of 2 kinds, the submerged 

 with blades 5-15 cm. long, the floating ones with elliptic, nearly sessile blades 3-10 cm. 

 long: drupelets 2.5-3.5 mm. long, 3-keeled, abruptly pointed. [P. Zisii Eoth.] 



In lakes and rivers, Maine to California, Florida, Texas and Central America. Also 

 in Europe. Summer. 



9. Potamogeton lucens L. Leaves of 1 kind, all submerged ; blades elliptic or 

 lanceolate, or oval above, 5-20 cm. long, acute or acuminate and often serrulate at 

 the apex, nearly sessile: drupelets 3 mm. long, blunt-tipped. 



In ponds. Nova Scotia to California, Florida and Mexico. Also in the West Indies and 

 Europe. Fall. 



10. Potamogeton perfoliatus L. Leaves submerged ; blades suborbieular to 

 ovate or lanceolate, 2-4 cm. long, usually obtuse and serrulate at the apex, cordate- 

 perfoliate: drupelets 2.5-3 mm. long, obscurely 3-keeled. 



In rivers and ponds, throughout the United States and southern Canada. Also in 

 Europe. Summer and fall. 



11. Potamogeton Curtissii Morong. Leaves submerged; blades linear-filiform, 

 1-4 cm. long. 1-ribbed, hair-tipped: drupelets not seen. 



In tidal creeks, Blackwater River, Florida. Spring and summer. 



12. Potamogeton foliosus Kaf. Leaves very many, submerged; blades linear 

 or filiform. 1.5-5 cm. long, 3-ribbed, acute: drupelets 1.5-2 mm. long, the middle 

 keel crest-like. 



In streams and ponds. New Brunswick to British Columbia, Florida and Mexico. Also 

 in the West Indies. Summer. 



13. Potamogeton pusillus L. Leaves numerous, submerged; blades linear or 



linear-filiform, 2-8 cm. long, 3-ribbed, acute: drupelets 1.5-2 mm. long, the middle 



keel not crest like, or obsolete. 



In slow streams and ponds. Nova Scotia to British Columbia, North Carolina, Louisiana, 

 California and Mexico. Also in Europe. Summer. 



14. Potamogeton diversifolius Eaf . Leaves of 2 kinds, the submerged linear- 

 setaceous, the floating ones elliptic, oval or oblong-lanceolate, 1-2.5 cm. long: 

 drupelets about 1 mm. long, the middle keel crest-like. 



In pools and still water, Maine to California, Florida, Texas and Mexico. Also in the 

 West Indies. Spring and summer. 



15. Potamogeton pectin^tus L. Leaves of 1 kind, all submerged, setaceous or 

 filiform, 2-15 cm. long: drupelets 1.5 mm. long, crestless. 



In still or running water, throughout the United States and southern Canada. Also in 

 Cuba and Europe. Summer and fall. 



Family 2. ZOSTER ACE AE Dumort. Eel-grass Family. 



Marine herbs. Leaves alternate : blades narrow, the bases inflated. Flowers 

 monoecious, alternating on a flat spadix; staminate a sessile anther; pistillate 

 an ovary with a style and two capillary stigmas. Fruit utricular. 



1. ZOSTERA L. 



Characters of the family. Eel-grass. Grass-wrack, 



1. Zostera marina L. Leaf -blades linear, 3.5-5 mm. wide: spadix 2.5-6.5 cm. 

 long: seeds about 20-ribbed. 



In streams or ditches, mostly near or on the coast, Greenland and Labrador to Florida. 

 Also from Alaska to California, and on the coasts of Europe. Summer — The imperfect 

 specimen referred to Zostera minor, by Morong, Mem. Torrey Club 3^ : 63, and admitted in 

 the first edition of this Flora, is Cymodocea manatorum Aschers. 



Family 3. CYMODOCEACEAE Kerner. Cymodocea Family. 



Submerged herbs with jointed rootstocks. Leaves clustered at the nodes 

 or on short branches, each with a sheath and a narrow blade. Flowers monoe- 

 cious or dioecious. Perianth wanting. Androecium of a pair of anthers termi- 

 nating a long stalk. Gynoecium of 2 united carpels, terminating in a style and 

 2 elongate stigmas, or of 1 carpel. Fruit an oblique nutlet. 



Anthers equally attached to the stalk: stigmas 2: leaf-blades terete or nearly so. 1. Cymodocea. 

 Anthers unequally attached to the stalk: stigma 1: leaf-blades flat. 2. Halodule. 



