NAIADACEAE. 



i. Zannichellia palustris L 

 nichellia. (Fig. 178.) 



Zan- 



Zannichellia palustris L. Sp. PI. 969. 1753. 



Stems capillary, sparsely branched, the 

 rhizome creeping, the roots fibrous. Lea% 

 i '-3' long, X" or l ess wide, acute, thin, i- 

 nerved with a few delicate cross-veins ; 

 spathe-like envelope separate from the leaves 

 and fruits at maturity ; fruits 2-6 in a cluster, 

 i"-2" long, sometimes sessile, sometimes 

 pedicelled, sometimes the whole cluster 

 peduncled ; style persistent, straight or 

 curved, ^ // -i // long ; plant flowering and 

 ripening its fruit under water. 



In fresh or brackish ponds, pools or ditches, 

 nearly throughout North America, except the 

 extreme north, and widely distributed in the 

 Old World. July-Sept. 



4. NAIAS L. Sp. PI. 1015. 1753. 



Slender, branching aquatics, wholly submerged, with fibrous roots. Leaves opposite, 

 alternate or verticillate, sheathing at the base. Flowers monoecious or dioecious, axillary, 

 solitary, sessile or pedicelled. Sterile flower with a double perianth, the exterior one entire 

 or 4-horned at the apex, the interior one hyaline, adhering to the anther ; stamen sessile or 

 stalked, i-4-celled, apiculate or 2-lobed at the summit. Fertile flowers of a single ovary 

 which tapers into a short style ; stigmas 2-4, subulate. Mature carpel solitary, sessile, ellip- 

 siod, its pericarp crustaceous. Seed conformed to the pericarp and embryo to the seed, the 

 raphe distinctly marked. [Greek, a water-nymph.] 



About 10 species, occurring in fresh water all over the world. The following are the only ones 

 known in North America: 



Sheaths broadly rounded, their margins entire or with a few large teeth. i. N. marina. 

 Sheaths narrowly and obliquely rounded, each margin with 5-10 minute teeth; leaves linear. 



2. X.fle.vilis. 



3. A'. Guadalupensis. 



4. A r . gracillima. 



Seeds shining, with 30-50 rows of faint reticulations. 

 Seeds dull, with 16-20 rows of strongly marked reticulations. 

 Sheaths auriculate; leaves delicately filiform. 



i. Naias marina L. Large Naias. 

 (Fig. 179.) 



A'a/05 marina I. Sp. PI. 1015. 1753. 



If major All. Fl. Ped. 2 : 221. 1785. 

 Dioecious, stem stout, compressed, commonly armed 

 with teeth twice as long as their breadth. Leaves op- 

 posite or verticillate, 6"-i2" long, about i" wide, with 

 6-10 spine-pointed teeth on each margin and fre- 

 quently several along the back ; sheaths with rounded 

 lateral edges; fruit large, a'^z^" long, the pericarp 

 as well as the seed rugosely reticulated, tipped with a 

 long persistent style and 3 thread-like stigmas ; seed 

 not shining. 



In lakes, Central New York to Florida, west to Califor- 

 nia. Summer. Also in Kurope. 



Naias marina gracilis Morons. Coult. Hot. Gaz. 10: 255. 1885. 

 Inti modes I'-j' long, with a few teeth on the upper part- 

 leaves scarcely '. " \vi,U . with 15-24 large teeth on the mar- 

 gins and a frw on tin- hack : slu-aths with 2 or 3 teeth on 

 each margin; seed sculptured with about 25 rows of nearly 

 square or irregularly oblong reticulations. Central New York and Florida. 



Wau marina recurvata Dudley, Ca3-uga Fl. 104. 1886. 



Branches and leaves recurved ; leaves 3" -6" long, narrow, with 2-4 large teeth on each margin 

 d none on the back ; internodes short, naked, or with i or 2 teeth ; sheaths i-toothed on each 

 aide. Cayuga Mar-ht-. N. Y. 



