I 



NAIADACE^. (rONDWKll) lAMlI.V.) 557 



Okdkk \2l). NAIADACE^. (roM)\vi.i:i> Family.) 



Marsh or mostly immersed aquatic herbs, with stems jointed and leafy or 

 (in Triglochin) naked and scape-like, leaves sheathing at base or stipulate, 

 and Jlowers perfect or unisexual, often spathaceous, with perianth of A or 6 

 herbaceous distinct valcate segments, or membranous and tubular or cup- 

 shaped, or none. Stamens 1, 2, 4 or 6, with extrorse anthers. Ovaries 

 l-d, distinct or more or less coherent, 1-celieti, nsually l-ovuled. in fruit 

 follicuhir or capsuhir or an indehiscent berry or utricle. 



SunoRDKK I. Jiincagineai. Marsh plants, with terete bladelcss 

 leaves; flowers perfect, spicate or racemose, with herbaceous G- (rarely 

 a-) lobed perianth; earjiels 3 or 6, more or less united, separating at 

 maturity. Seeds anatropous ; embryo straight. 



1. Triglochin. Ovaries 3-6, united until maturity. Leaves radical. Flowers bractless, 



ill ;i hiiii<e-lii<e raceme terminating a jointless scape. 



2. Scheuchzeria. Ovaries 3, nearly distinct, at length divergent. Flowers bracteate iu a 



loo6e raceme upon a leafy stem. 



Suborder 11. Naiadeae. Immersed aquatics, with flat leaves; 

 ovaries solitary or distinct, l-ovuled. 



■t- Flowers peilect, spiked or clustered ; anthers 4 or 2, sessile ; leaves alternate. 



3. Potaniogeton. Spike peduncled. Sepals 4, herbaceous. Anthei-8 4. Ovaries 4, sessile, 



4. Ruppia. Flowers on an enclosed spadix, at length loug-exserted, without perianth. 



Anther-cells 4, distinct. Ovaries 4, becoming .stipitate. 

 -4- -t- Flowers monoecious or dioecious, axillary, naked, monandrous ; leaves opposite (alter- 

 nate in n. 6). 



5. Zannicliellia. MonfEcious. Pistils (2 - 5) from a cup-shaped involucre or sheath. 



6. Zostera. Pistils and stamens alternate in 2 vertical rows on the inner side of a leaf-like 



enclosed spadix. Stigmas 2, linear. Stem creeping. 



7. Naias. Dioecious ; pistil solitary, naked. Stamen enclosed in a membranous spathe. 



Stems floating, witli opposite or ternate leaves, 



1. TRIGLOCHIN, L. Arrow-grass. 



Sepals and petals nearly alike (greenish), ovate, concave, deciduous. 8t;v 

 mens 3-6; antliers oval, on very short fdaments. Pistils united into a 3-6- 

 celled compound ovary ; stigmas sessile ; ovules solitary. Capsule splitting 

 when ripe into 3-6 carpels, which .separate from a persistent central axis. — 

 Perennials, with rush-like, fleshy leaves, below sheathing the base of the wand- 

 like naked and jointless scape. Flowers small, in a spiked raceme, bractless. 

 (Name composed of rp^ii, three, and yXcox'^fy p^int, from the three points of 

 the ripe fruit in n. 1 when dehiscent.) 



* Fruit of 3 carjiels. 



1. T. palustris, L. Scape (6-18' high) and loaves slender; sepals and 

 siomens 6; fruit linpar-cluh-shaped ; carpels when ripe separating from below 

 upward, leaving a triangular axis, awl-pointed at base. — Marshes, western 

 N. Y. to 111., Minn., and westward. Aug. (Eu., Asiji, etc.) 



2. T. striata, Ruiz & Pav. Scape (6-12' high) and leaves slender; fi<t\v- 

 ers very small; sepals and stamens 3; fruit glohose-trianr/nlar, or when dry 

 3-lobed. (T. triandra, Mich.r.) — Sea-ahore, Md. to Fla. (S. Am., etc.) 



