JUNCAGINACEAE (ARROW GRASS FAMILY) 79 



and containing a tuft of threads in place of ordinary pollen ; the fertile of single 

 ovate-oblong ovaries attached near their apex, tapering upward into an awl- 

 shaped style, and containing a pendulous orthotropous ovule ; stigmas 2, long 

 and bristle-form, deciduous. Utricle bursting irregularly, inclosing an oblong 

 longitudinally ribbed seed (or nutlet). Embryo short and thick (proper cotyle- 

 don almost obsolete), with an open chink or cleft its whole length, from which 

 protrudes a doubly curved slender plumule. Grass-like marine herbs, growing 

 wholly under water, from a jointed creeping stem or rootstock, sheathed by the 

 bases of the very long and linear obtuse entire grass-like ribbon-shaped leaves 

 (whence the name, from facrr-ftp, a belt}. 



1. Z. marina L. Leaves obscurely 3-5-nerved. Shoal water of bays along 

 the coast, Nfd. to Fla. ; Pacific coast. (Eurasia.) 



5. NAjAS L. NAIAD 



Flowers dioecious or monoecious, axillary, solitary, and sessile ; the sterile 

 consisting of a single stamen inclosed in a little membranous spathe ; anther at 

 first nearly sessile, the filament at length elongated. Fertile flowers consisting 

 of a single ovary tapering into a short style ; stigmas 2-4, awl-shaped ; ovule 

 erect, anatropous. Fruit a little seed-like nutlet, inclosed in a loose and sepa- 

 rable membranous epicarp. Embryo straight, the radicular end downward. 

 Slender branching herbs, growing under water, with opposite and linear leaves, 

 somewhat crowded into whorls, spinulose-toothed, sessile and dilated at base. 

 Flowers very small, solitary, but often clustered with the branch-leaves in the 

 axils ; in summer. (Nai'ds, a water-nymph.} 



1. N. marina L. Stem rather stout and often armed with broad prickles ; 

 leaves broadly linear (2 mm. broad}, coarsely and sharply toothed, the dilated 

 base entire ; fruit 4-5 mm. long; seed very finely lineate, oblong, slightly com- 

 pressed. Marshes and salt springs of w. N.Y., Mich., and Minn.; Fla.; Utah to 

 Mex. Teeth of one or more brownish cells upon a many-celled base. (W. I., 

 Eurasia, Austr.) 



Var. gracilis Morong. Internodes long (5-8 cm.) and nearly naked, with 

 only a few teeth above ; leaves very narrow (0.5 mm. wide) with 8-12 teeth 

 on each margin, the dilated base also toothed ; fruit smaller. Canoga marshes, 

 w. N. Y.; Fla. 



Var. recurvata Dudley. Stems short, inclined to be dichotomously branched, 

 recurved-spreading ; leaves usually recurved, the teeth prominent, 2-7 on each 

 margin, the dilated base with a projecting tooth each side. N. Y. ; Utah and Ariz. 



2. N. flxilis (Willd.) Rostk. & Schmidt. Stems usually very slender ; leaves 

 very narrowly linear (less than 1 mm. wide), very minutely serrulate, tapering 

 gradually to the serrulate base; fruit 2. 5-3 mm. long, narrowly oblong; seeds 

 lance-oval, smooth and shining. Ponds and slow streams, Lab. to B. C., s. to 

 S. C. and Mo. Teeth on the margins of the leaves 1-celled. (Eu.) Var. 

 ROBUSTA Morong. Stem stout, few-leaved, sparsely branching, elongated ; leaves 

 flat, strongly ascending, linear-tapering. Mass, to Mich, and Tex. 



3. N. guadalupSnsis (Spreng.) Morong. Similar; leaves with 20-45 very 

 minute teeth on each margin ; fruit 2 mm. long ; seeds dull, conspicuously 

 reticulate. (N. microdon A. Br.) Pa. to Neb., and southw. (Trop. Am.) 



4. N. gracillima (A. Br.) Magnus. Branches alternate; leaves very nar- 

 rowly linear, nearly capillary, straight, serrate, the rounded lobes of the sheath- 

 ing base spinulose-ciliate ; fruit linear, impresses-dotted between the numerous 

 ribs. (N. indica, var. A. Br.) Local, e. Mass. toe. N. Y., N. J., and Pa. ; Mo. 

 Teeth of 3 cells each. 



JUNCAGINACEAE (ARROW GRASS FAMILY) 



Marsh plants, with terete bladeless leaves. Flowers perfect, spicate or 

 racemose, with herbaceous 6(rarely %}-lobed perianth. Carpels 3 or 6, more 

 or less united, separating at maturity. Seeds anatropous; embryo straight. 

 Fruit follicular or capsular. 



