552 ORDER CXXXIX. NAIADACEJi:. 



Genus VII.— LEM'NA. L. 19—2. 

 (From lemina, a liusk.) 



Flowers monoecious, with tlie sterile and fertile flowers col- 

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



1. L. mi'nor, (L.) a small floating plant. Leaves elliptic, flat, bear- 

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

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

 waters. 



2. L. poLYRHi'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 VIIL— PIS'TIA. L. 5—8. 

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



Perianth tubular, cucullate ; spathe strap-shaped. • Stamens 

 3 — 8. Caj^sule 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. @. May — Aug. In 

 stagnant waters. 



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



(^Pond-weed Family.) 



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

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

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

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

 with cellular leaves. 



Genus I— ZOS'TERA. L. 21—1. 

 (From zoster, a girdle.) 



i^/o^i'frs monoecious. Perianth none. Stamens a.nd jnstils 

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

 foliaceous. Anthers sessile, alternating with the ovaries. Drupe 

 1 -seeded. 



1. Z. mari'na, (L.) Stem flexuous, terete, somewhat jointed. Leaves 

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

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



Grass-wrack. 



Genus II.— CAULIN'IA. D. C. 19— 1. {Najos.) 

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



Flowers monoecious. Perianth none. Anther 1, sessile. 

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



