342 HYDROCHARIDACE^. 



Class II. ENDOGENOUS or MONOCOTYLEDO- 

 NOUS PLANTS. 



Stem, with no perceptible distinction of bark, wood and pith, 

 increasing in diameter by the addition of new matter to the 

 centre. Leaves mostly alternate, with no evident articulation, 

 commonly sheathing at base and entire, mostly with parallel 

 veins. Embryo with but one cotyledon; or if two, one is 

 smaller and alternate with the other. 



Subclass L— PETALOIDEALS. 



Stamens and pistils naked or covered by verticillate floral 

 envelopes. 



Order CXXIV. HYDROCHARIDACE^.— Frog's Bits. 



Flowers in a spathe, mostly dioecious. Perianth regular, 

 3 — 6-parted ; the inner segments petaloid. Stamens 3 — 12. 

 Ovary 1 — 9-celled ; stigmas 3 — 6. Fruit dry or succulent, in- 

 dehiscent. Seeds numerous, without albumen. — Floating or 

 Water plants. Leaves mostly radical, sometimes opposite or 

 verticillate. 



1. UDORA. Nutt.—Vdora. 

 (From the Greek vSaip, water ; in allusion to its place of growth.) 



Polygamous. Spathe bifid, 1 -flowered. Perianth 6-parted, 

 petaloid. Sterile Fl. Stamens 9, 3 of them interior.. Per- 

 fect Fl. Tube of the perianth veiy long and slender. •Sta- 

 mens 3 — 6 ; filaments short, subulate. Style long and filiform. 

 Stigmas 3, large and spreading, 2-lobed. Fruit coriaceous, 

 few seeded. Seeds eUiptic, smooth. 



U. Canadensis Nutt. : leaves verticillate in threes and fours, lanceolate, 

 oblong or linear, finely serrulate ; tube of the perianth filiform. Elodea 

 Canadensis Mich. Serpicula verticillata Muhl. 



Still waters. Can. to Virg. W.* to Miss. Aug.. T].? — (Sfero submersed, dif- 

 fiisely dichotomous. Flowers axillary, very small, w^hitish. The plant without 

 flowers resembles an aquatic moss. Little Water Snakeweed. 



2. VALLISNERIA. I/mTi.— Tapeweed. 

 (In honor of Antonio VallisnerL an Italian botanist.) 



Dioecious. Sterile Fl. Spathe ovate, 2 — 4-parted. Spa- 

 dix covered with minute flowers. Perianth 3 -parted. Stamens 



