5O FLORA. 



1. Ruppia maritima L. MARITIME RUPPIA. (I. F. f. 176.) Stems usually 

 whitish, often I m. long, the internodes irregular, naked. Leaves 2-8 cm. long, 

 1.5 mm. or less wide; sheaths with a short free tip; peduncles in fruit 

 sometimes 0.3 m. long; pedicels 4-6 in a cluster, 13.5 cm - ^ on S5 drupes 

 with a dark hard shell, ovoid, about 2 mm. long, often oblique or gibbous 

 at the base, pointed with the long style, but varying much in shape; 

 forms with very short peduncles and pedicels, and with broad, strongly marked 

 sheaths occur. Common in brackish or salt water along the Atlantic and Pacific 

 Coasts of N. Am. and in the saline districts in the interior. Widely distributed in 

 the Old World and in S. Am. July-Aug. 



2. Ruppia occidentals S.Wats. WESTERN RUPPIA. (I. F. f. 177.) Stems 

 stouter, the branching fan-like. Leaves 7-20 cm. long, with large branches and 

 leaves often thickly clustered at the nodes, the sheaths overlapping each other; 

 drupes larger, ovoid or pyriform, borne on pedicels about 2 mm. long, the peduncles, 

 bright red when fresh and sometimes nearly 0.7 in. in length. In saline ponds, 

 Neb. to Br. Col. Summer. 



3. ZANNICHELLIA L. 



Stems, flowers and leaf-buds all at first enclosed in a hyaline envelope, corre- 

 sponding to the stipule in Potamogeton. Staminate and pistillate flowers in the 

 same axil; the stamina te solitary, consisting of a single 2 -celled anther, borne on a 

 short pedicel-like filament; the pistillate 2-5. Ovary flask-shaped, tapering into 

 a short style; stigma broad, hyaline, somewhat cup-shaped, its margins angled or 

 dentate. Fruit a flattish falcate nutlet, ribbed or sometimes toothed on the back. 

 Embryo bent and coiled at the cotyledonary end. [In honor of J. H. Zannichelli, 

 1662-1729, Italian physician and botanist] Two or three species of very wide 

 geographical distribution in fresh-water ponds and streams. 



I. Zannichellia palustris L. ZANNICHELLIA. (I. F. f. 178.) Stems capillary, 

 sparsely branched, the rhizome creeping; roots fibrous. Leaves 2-7 cm. long, 0.5 

 mm. or less 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, 

 2-4 mm. long, sometimes sessile, sometimes pedicelled, sometimes the whole cluster 

 peduncled; style persistent, straight or curved, 1-2 mm. long; plant flowering and 

 ripening its fruit under water. In fresh or brackish ponds, pools or ditches, nearly 

 throughout N. Am., except the extreme north, and widely distributed in the Old 

 World. July-Sept. 



4. NAIAS L. 



Slender, branching aquatics, wholly submerged, with fibrous roots. Leaves oppo- 

 site, 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, subu- 

 late. Mature carpel solitary, sessile, ellipsoid, its pericarp crustaceous. Seed con- 

 formed 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 N. Am. : 



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. 



Seeds shining, with 30-50 rows of faint reticulations. 2. N.flexilis. 



Seeds dull, with 16-20 rows of strongly marked reticulations. 3. .A 7 . Guadalupensis* 

 Sheaths auriculate ; leaves delicately filiform. 4. N. gracillima. 



I. Naias marina L. LARGE NAIAS. (I. F. f. 179.) Dioecious; stem stout, 

 compressed, commonly armed with teeth twice as long as their breadth. Leaves 

 opposite or verticillate, 12.5 cm - l n g> about 2 mm. wide, with 6 10 spine-pointed 

 teeth on each margin and frequently several along the back; sheaths with rounded 

 lateral edges; fruit large, 4-5 mm. long, the pericarp tipped with a long persistent 



