1. Najas L. Water-nymph 



Characters of the family. 



The species in this genus, along with those in Potamogeton, are considered 

 by knowledgeable wildlife personnel to provide the most important source of all 

 foods for wildfowl, marshbirds and shorebirds. Ducks and other waterfowl not 

 only eat the seeds but also the stems and leaves of most of the species. The 

 species are also considered to be good food producers for fish and to provide 

 shelter. 



1. Male and female flowers on different plants; leaves coarsely toothed; inter- 

 nodes and back of the leaf spiny 1. N. marina. 



1. Male and female flowers on same plant; leaves minutely denticulate; internodes 



and back of leaf unarmed (2) 



2(1). Seeds dull, with distinct squarish pitted reticulations; leaves tapered for 

 2-3 mm. to an acute to obtuse apex 2. TV. guadalupensis. 



2. Seeds apparently smooth and shining (but finely reticulate under magnifica- 



tion); leaves tapered from near middle to a long slender point 



3. N. fiexilis. 



1. Najas marina L. Holly-leaved water-nymph. Fig. 50. 



Plants brittle; stems branched, sometimes dichotomously so, armed with 

 brownish spinulose teeth on the internodes; leaves linear, opposite to somewhat 

 alternate, stiffish or recurved, to 45 mm. long and 3 mm. wide, with toothed 

 margins and sometimes dorsally toothed on the midrib, the usually triangular 

 teeth apiculate and 1 mm. long or more; basal leaf sheaths rounded, without 

 teeth or rarely with a few short teeth; male and female flowers on different plants; 

 staminate flowers 3-4 mm. long, the anther 4-celled; pistillate flowers 3-4 mm. 

 long; stigmas 3, sometimes one shorter than the others; mature seeds ovoid, 

 apparently tesselated in dried specimens, smooth when fresh. 



In lakes and ponds, rare in s. Tex. and Ariz. (Mohave, Navajo, Pima, Santa 

 Cruz and Yuma cos.), May-Sept.; from N.Y. to Cahf., s. to Fla., Tex., Ariz., 

 Mex. and Cuba; also Euras. and Austral. 



2. Najas guadalupensis (Spreng.) Magnus. Common water-nymph. Fig. 51. 



Plants monoecious, flaccid; stems slender, branched, to about 6 dm. long; 

 leaves all submerged, linear, to 25 mm. long and 2 mm. wide, tapered for 2-3 

 mm. to an acute to obtuse apex and usually tipped with 1 or 2 spines, the 20 to 40 

 marginal teeth inconspicuous or often apparently wanting; basal leaf sheaths 

 sloping or rounded, not auriculate, spinulose; male and female flowers on same 

 plant; staminate flowers 2-3 mm. long, the anthers 4-celled; pistillate flowers 2-3 

 mm. long; mature fruit crowned with 2 or 3 stigmas and usually with 1 or 2 

 spiny sterile stigmatic processes; seeds ellipsoid, dull, reticulate with numerous 

 4-sided areolae. 



Attached to bottom and floating just below surface of water in ponds, lakes, 

 springs, ditches and streams, in fresh or sometimes brackish water, often forming 

 large mats, rather common throughout Tex. and Okla., rare in N.M. (Rio Arriba 

 Co.) and Ariz. (Santa Cruz and Yavapai cos.), Apr. -Sept.; from Pa. w. to Ore., 

 s. to Fla., Tex., N.M., Ariz., Mex., C.A., the W.I., Jam. and Guadeloupe. 



3. Najas flexilis Rostkov. & Schmidt. Slender water-nymph. Fig. 52. 



Plants monoecious; stems freely branched, slender, to 2 m. long; leaves narrowly 

 linear, 1-3 cm. long, less than 1 mm. wide tapered from about the middle to a long 

 slender point, thin and translucent, very minutely toothed, numerous and crowded 

 on the upper parts of the branches, the teeth consisting of protrusions of usually 

 1 marginal cell; leaf sheaths with obliquely sloping shoulders, the margins bearing 



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