Fam. 17. Ruppiaceae Hutchins. Ditch-grass Family 



Aquatic herbs of brackish or saHne waters; stems simple or branched, sub- 

 merged; leaves opposite or alternate, linear or setaceous, with a stipular sheath 

 at the base; flowers perfect, small, few, arranged in terminal spikes that are 

 at first enclosed by the sheathing leaf bases, at length much-elongated to the 

 surface of the water; bracts absent; perianth wanting; stamens 2, opposite each 

 other, with very short broad filaments; anthers extrorse, the 2 cells reniform 

 and separated by the connective; carpels 4, with peltate or umbonate stigmas; 

 ovule solitary, pendulous from the apex of the carpel, campy lotropous; nutlets 

 long-stipitate, with spirally twisted stalks, indehiscent; seeds pendulous, without 

 endosperm. 



Only one genus distributed throughout temperate and subtropical regions. 



1. Ruppia L. 



Characters of the family; 2 species. 



1. Ruppia maritima L. Widgeon-grass. Fig. 49. 



Stem whitish or green, to 1 m. long; leaves all submerged, threadlike, entire, 

 1-nerved, to 1 dm. long and 0.3 mm. wide, with a sharp pointed or more or less 

 pungent apex; stipular sheath 6-10 mm. long, membranous, the free part very 

 short or wanting; flowers on a short peduncle that elongates after anthesis and 

 ultimately becomes a loosely coiled spiral; stamens without a filament, early 

 deciduous; anthers 2, sessile, 2-celled; mature carpels ovoid, equilateral or gibbous 

 and oblique, about 2 mm. long, long-stipitate; style short and stout or finely 

 attenuate, straight or hooked; pedicellate stipe of the black nutlet to 3 cm. long. 



On the Tex. Gulf Coast and in saline waters of pools, rivers and marshes in 

 the interior to Okla. (Alfalfa Co.), N.M. (Chaves Co.) and Ariz. (Maricopa, 

 Mohave and Navajo cos.), Apr. -Aug.; from Can. s. to Mex. 



This species is considered to be one of the most valuable of all submerged 

 aquatics, especially in saline habitats, for the maintenance of wild life. It 

 provides excellent food and cover for fish, and all parts of the plant, including 

 its rootstock and stems, are relished by many species of waterfowl, while marsh- 

 birds and shorebirds eat its fruit and foliage. 



Fam. 18. Najadaceae Juss. Water-nymph Family 



Submerged annual monoecious or dioecious herbs of fresh or brackish waters, 

 with fibrous roots; stems slender, much-branched; internodes spiny or unarmed; 

 leaves small, sessile, subopposite to somewhat alternate or verticillate, with a 

 sheathing base and linear entire or toothed blade; within the sheath a pair of 

 minute scales; flowers unisexual, very small, borne at the base of the branches; 

 staminate flowers with 1 stamen, mostly subsessile and included in a spathe, the 

 perianth bilabiate at the apex; anther sessile, 1- to 4-celled, opening by slits 

 lengthwise; pistillate flowers without a perianth or this very thin and adhering 

 to the carpel; ovary of 1 carpel, 1 -celled, with 2 to 4 linear stigmas; ovule 

 solitary, erect from the base, anatropous; nutlet usually embraced by the leaf 

 sheath, indehiscent, enclosed in a loose and separable membranous coat, smooth 

 and shining or reticulate with angled or roundish areolae. 



Contains only the following genus and about 50 species widely distributed in 

 temperate and warm regions. 



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