80 NAIADACEAE. 
1. Zannichellia palustris Ll. Zan- 
nichellia. (Fig. 178.) 
Zannichellia palustris V,. Sp. Pl. 969. 1753. 
Stems capillary, sparsely branched, the 
rhizome creeping, the roots fibrous. Leaves 
1/-3’ long, 4’’ or less wide, acute, thin, 1- 
nerved with a few delicate cross-veins ; 
spathe-like envelope separate from the leaves 
and fruits at maturity ; fruits 2-6 in a cluster, 
1/’-2’’ long, sometimes sessile, sometimes 
pedicelled, sometimes the whole cluster 
peduncled; style persistent, straight or 
curved, 14’/-1’’ 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 
vi Old World. July-Sept. 
4. NAIAS IL, Sp. Pl. rors. 753- 
Slender, branching aquatics, wholly submerged, with fibrous roots. Leaves opposite, 
alternate or verticillate, sheathing at the base. Flowers monoccious 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, 1-4-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. 1. VV. marina. 
Sheaths narrowly and obliquely rounded, each margin with 5-10 minute teeth; leaves linear. 
Seeds shining, with 30-50 rows of faint reticulations. N. flexilts. 
Seeds dull, with 16-20 rows of strongly marked reticulations. N. Guadalupensis. 
Sheaths auriculate; leaves delicately filiform. N. gracillima. 
2. 
ae 
4. 
1. Naias marina Ll. Large Naias. 
(Fig. 179.) 
Natas marina V,. Sp. Pl. 1015. —1753- 
Naias 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’’-12’’ long, about 1’’ wide, with 
6-10 spine-pointed teeth on each margin and fre- 
quently several along the back; sheaths with rounded 
lateral edges; fruit large, 2’’-214’’ 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 Europe. 
Naias marina gracilis Morong, Coult. Bot. Gaz. 10: 255. 1885. 
Internodes 1’—3' long, with a few teeth on the upper part; 
leaves scarcely \'’ wide, with 15-24 large teeth on the mar- 
gins and a few on the back; sheaths with 2 or 3 teeth on 
each margin; seed sc ulptured with about 25 rows of nearly 
square or irregularly oblong reticulations. Central New York and Florida. 
Naias marina xecurvata Dudley, Cayuga Fl. 104. 1886. 
Branches and leaves recurved ; leaves 3''-6'’ long, narrow, with 2-4 large teeth on each margin 
and none on the back ; internodes short, naked, or with 1 or 2 teeth; sheaths 1-toothed on each 
side. Cayuga Marshes, N. Y. 
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