552 ORDER CXXXIX. NAIADACEJS. 



Genus VII.— LEM'NA. L. 19—2. 

 (From lemina, a husk.) 



Flowers monoecious, with the sterile and fertile flowers col- 

 lateral. Stamens 2. Capsule 1-ceiled, 1 — 5-seeded. 



1. L. mi'nou, (L.) A small floating plant. Leaves elliptic, flat, bear- 

 ing flowers in clefts, on the margins of the leaves or fronds. Hoot sol- 

 itary. Plants increasing by gemmae. — 0. July — Aug. In stagnant 

 waters. 



2. L. roLYRHi'zA, (L.) Leaves elliptic, flat, cohering at the base, 

 compressed, succulent, of a firm texture. Root a bundle of 8 — 10 sim- 

 ple fibers, in the middle of the leaf. — ©. June — July. In stagnant 

 waters, rare. Spirodela polyrhiza, Sch. 



Genus VIII— PISTIA. L. 5—8. 

 (From pistos, to drink, from its loving water.) 



Perianth tubular, cucullate ; spathe strap-shaped. Stamens 

 3 — 8. Capsule 1-celled, many-seeded. 



1. P. spathula'ta, (Mich.) A floating plant. Leaves all radical, ab- 

 ruptly narrowed into a petiole, dilated, round and obtuse toward the 

 summit. Flowers solitary, sub-sessile. — White. 0. May — Aug. In 

 stagnant waters. 



Order CXXXIX.— NAIADA'CE^E or POTA'ME^E. 

 (Pond-weed Family.) 



Flowers monoecious or perfect. Perianth 2 or 4-parted, or 

 none. Stamens hypogynous, definite. Ovary superior, with a 

 solitary ovule. Stigma simple. Fruit indehiscent, 1-celled, 

 1-seeded, dry. Seed pendulous, anatropous. Aquatic plants, 

 with cellular leaves. 



Genus I.— ZOSTER A L. 21—1. 

 (From soster, a girdle.) 



Flowers monoecious. Perianth none. Stamens and pistils 

 separated, in two rows, upon one side of the spadix. Spathe 

 foliaceous. Anthers sessile, alternating with the ovaries. Drupe 

 1-seeded. 



1. Z. maiu'na, (L.) Stan flexuous, terete, somewhat jointed. Leaven 

 long, linear, entire, somewhat 3-uerved. Anther slightly curved. Style 

 short. Capsule membranaceous. — If. August. Salt-waters. 



Grass-icrack. 



Genus II.— CAT UN" I A. D. C. 19— 1. (Xajos.) 

 (In honor of F. Cavolini, a botanist of Naples.) 



Flowers monoecious. Perianth none. Anther 1, sessile. 

 Style filiform. Stigma 2-cleft. Capsule 1-seeded, 



