42 NAIADACEAE 



1. CYMODOCEA Koenig. 

 Eootstocks elongated. Leaves terete or half-terete above the sheaths. Flowers 

 hidden in the leaf-sheaths or the staminate long-exerted. 



1. Cymodocea manatorutn Aschers. Plants growing on sandy bottoms, the 

 short stems arising from the nodes of the rootstock: leaf -blades narrowly linear, 5-25 

 cm. long: nutlets 6-7 mm. long, short-stipitate, prominently beaked. 



In bays, Florida to Mississippi and Louisiana. Also in the West Indies. 



2. HALODULB Endl. 

 Eootstocks elongated. Leaves flat above the sheaths. Flowers borne in the 

 leaf -sheaths or the staminate long-exserted. 



1. Halodule Wrightii Aschers. Plants growing on sandy bottoms, the short 

 stems arising from the nodes of the rootstock: leaf -blades narrowly linear, 3-40 em. 

 long: nutlets sessile. 



In bays and creeks, southern Florida. Also in the West Indies. 



Family 4. NAIADACEAE Lindl. Naias Family. 



Mostly fresh-water herbs. Leaves mainly opposite: blades mostly toothed, 

 the bases dilated. Flowers dioecious, axillary; staminate a single stamen and a 

 double perianth; pistillate an ovary with a style and 2 or 3 stigmas. Fruit 

 drupaceous. 



1. NAIAS L. 



Characters of the family. 



Flowers monoecious: internodes and lower surfaces of the leaves unarmed. 



Anthers 1-celled: seeds shining. 1. N./lexilis. 



Anthers 4-celled: seeds reticulated. 



Leaf-margins with minute subulate teeth. 2. N. Guadalupensis. 



Leaf-margins with prominent triangular teeth. 3. A'^. conferta. 



Flowers dioecious: internodes and lower surfaces of the leaves spiny. 

 Leaves about 0.5 mm. wide, with 15-24 marginal teeth: internodes 



filiform. 4. A'^. gracilis. 



Leaves about 2 mm. wide, with 6-10 marginal teeth: internodes stout. 5. A'', marina. 



1. Naias fl^xilis (Willd.) Eostk. & Schmidt. Stems slender: leaves more 



numerous, rather closer together and smaller than in the next following; blades 



mainly acuminate: drupelets 3^ mm. long. 



In streams and ponds, nearly throughout the United States, and in Mexico and Cuba. 

 Also in Europe. Summer. 



2. Naias Guadalupensis (Spreng.) Moroug. Stems capillary or filiform: leaves 



10-26 mm. long; blades acute: drupelets about 2 mm. long. 



In ponds and lakes, Pennsylvania to Oregon, Florida and Texas. Also in tropical 

 America. Summer and fall. 



3. Naias conf6rta A. Br. Similar to N. flexilis in habit, but the leaves more 

 slender, their margins prominently sharp-toothed. 



In tidal creeks, western Florida. Also in Cuba. Summer. 



4. Naias grdcilis (Morong.) Small. Stems filiform, the internodes slightly 

 armed near the top: leaf -blades slender, acuminate: drupelets mainly less than 4 mm. 

 long. 



In creeks and ponds, Florida. All year. 



5. Naias marina L. Stems stout, the internodes strongly armed throughout : 

 leaf -blades linear, acute : drupelets mainly over 4 mm. long. 



In lakes and rivers. New York to California and Florida, and in Mexico and Cuba. 

 Also in Europe and Asia. Summer. 



Order 3. ALISMALES. 



Marsh or aquatic herbs. Leaves alternate, mere phyllodia, or with dilated 

 blades. Flowers regular. Perianth of sepals and usually also petals. Androe- 

 cium of 3-6 stamens or more. Gynoeeium of 3-many carpels. 



Petals nearly similar to the sepals: carpels coherent. Fam. L Scheuchzeriaceae. 



Petals very different from the sepals: carpels not coherent. Fam. 2. Alismaceae. 



Family 1. SCHEUCHZERIACEAE Agardh. Arrow-grass Family. 



Perennial herbs. Leaves narrow or slender above the dilated bases. 

 Flowers perfect in spikes or racemes. Perianth herbaceous. Gynoeeium 3-6- 

 carpellary. Style wanting or obsolete. Fruit 3-6 turgid carpels. 



