Hydrocharis. HYDROCHARIDACEiE. 263 



Group 3. Flowers with a simple or double perianth, which coheres with the lower 

 part, or with the whole surface of the ovary, — Herbs. 



Order CXI. HYDROCHARIDACEiE. Juss. The Frog's-bit Tribe. 



Flowers mostly dioecious. Perianth regular, 3 - 6-parted ; the inner segments 

 petaloid. Stamens 3 - 12. Ovary one-celled, with 3-6 parietal placentae, 

 or 6-celled : stigmas 3 - 6 or 9, entire or 2-cleft, usually large. Ovules ana- 

 tropous or orthotropous. Fruit coriaceous or somewhat fleshy, indehiscent. 

 Seeds numerous. Embryo straight, without albumen. — Aquatic herbs ; the 

 leaves mostly radical, sometimes opposite or verticillate. 



CONSPECTUS OP THE GENERA. 



1. Htdsocharis. Dioecious or moncecious. Stamens 9. Stigmas 6, each 2-horned. Capsule roundish, 6-ceIIed, 



2. Udoba. Polygamous. Stee. fl. Stamens 9-12; 3 of them interior. Perfect fl. Stamens 3-6. Tube of 



the perianth very long and filiform. Stigmas 3, 2-cleft. Fruit one-celled. — Leaves caulescent, verticillate. 



3. Yalisneria. Dioecious. Stamens 3, one of them often abortive. Stigmas 3, 2-cIeft, seated on the summit of the 



ovary. Fruit one-celled. — Leaves radical. 



1. HYDROCHARIS. Linn.; Endl. gen. 1216. frog'S-BIT. 



[From the Greek, hydor, water, and charo, to rejoice ; because these plants live in the water. 



Flowers dioecious or monoecious. Sterile. Spathe at the summit of a short scape, 2-Ieaved, 

 about 3-flowered. Calyx deeply 3-parted ; the segments oval. Corolla of 3 roundish 

 petals. Stamens 9 - 12 : filaments united into a column below. Rudimentary ovary 3- 

 lobed. Fertile. Spathe radical, one-leaved. Flower on a long peduncle. Calyx deeply 

 3-parted. Petals 3. Abortive stamens 6, subulate. Style very short, thick : stigmas 6, 

 oblong-cuneate, divaricately 2-horned. Fruit ovoid, 6-celled. Seeds attached to the sides 

 of the dissepiment. — Perennial herbs, with floating stolons, reniform or cordate petiolate 

 leaves, and rather conspicuous white flowers. 



1, Hydrocharis cordifolia, Nutt. Heart-leaved Frog's-bit. 



" Monoecious "(iVw«.) ; leaves roundish-cordate ; sterile flowers on long peduncles ; fertile 

 on short peduncles ; anthers linear ; stigmas 6-7, two-parted nearly to the base, the seg- 

 ments lanceolate-subulate. — Nutt. gen. 2. p. 241. H. spongiosa, Bosc in ann. du mus. 9. 

 p. 396. t. 30 ; Ell. sk. 2. p. 714. 



Perennial, producing stolons from which new plants arise. Roots fibrillose. Leaves 



