252 



state of the calyx of Butomus itself. They are, however, readily known by the 

 remarkable circumstance of the placenta extending over the whole lining of the 

 fruit, which is formed either of separate or concrete carpella. In this respect 

 there is an evident analogy with Nymphseacese, which Limnocharis resembles 

 in the structure of its fruit. Butomere are most^ closely akin to Alismacese. 

 M. Decandolle has a remark (Syst. 2. 42.), that, no Endogenas are lactescent ; 

 but Limnocharis yields milk in abundance. This genus offers a singular ex- 

 ample of a large conspicuous open hole in the apex of its leaf, apparently des- 

 tined by nature as an outlet for superfluous moisture, which is constantly 

 distilling from it. 



Geography. Natives of the marshes of Europe, and equinoctial America. 



Properties. Butomus is acrid. 



Examples. Butomus, Limnocharis, Hydrocleys. 



CCXXXI. HYDROCHARIDEiE. The Frog-bit Tribe. 



Hydrocharides, Juss. Gen. 67. (1789). — Hydbocharii>ek, Dec. Fl. Fr. 3. 265. (1815); R. 

 Brown Prodr. 344. (1810) ; Richard in Mem. Mus. vol. i. 365. (1815) ; Agardh Aph. 127. 

 (1822) ; Lindlei/s Synopsis, 254. (1829). — VallisneriacEjE and STRATiOTEJE,'Link Handb 

 1.281.(1829) 



Diagnosis. Tripetaloideous monocotyledons, with an inferior ovarium, and 

 exalbuminous antitropous embryo. Water plants. 

 Anomalies. 



Essential Character. — Flowers monoclinous, or diclinous. Sepals 3, herbaceous. Pe- 

 tals 3, petaloid. Stamens definite or indefinite. Ovary single, inferior, 1- or many-celled ; 

 stigmas 3-6,- ovules indefinite, often parietal. Fruit dry or succulent, indehiscent, with 1 or 

 more cells. Seeds without albumen ; embryo undivided, antitropous. — Floating plants. Leaves 

 ■with parallel veins, sometimes spiny. Flowers spathaceous. 



Affinities. The water-plants are readily distinguished from all other mo- 

 nocotyledons by their tripetaloideous flowers, with an inferior ovarium : by this 

 they are separated from Alismacese, with which they agree in habit and want 

 of albumen, but from which they also differ, as Pomaces from Ranunculaces, 

 in the carpella being definite, not indefinite. Commelinea: are at once recog- 

 nised by their superior trilocular ovarium. Agardh refers here Trapa (see p. 

 58.) ; Linnaus placed Hydrochavidea; along with Palms ! in his natural ar- 

 rangement. 



Link defines his Hydrocharidea?, Stratioterp, and Vallisneriacese, thus : 



Hydrocharidece. Aquatic herbs. Leaves with parallel veins connected 

 with lateral ones ; sheath separate. Calyx divided to the base. Corolla poly- 

 petalous. Pericarpium. Albumen none, unless the thickened part of the em- 

 bryo. Hydrocharis. 



Strafiotece. Aquatic herbs. Leaves sheathing with parallel veins. Flowers 

 spathaceous. Calyx tubular. Corolla polypetalous, inserted on the calyx. 

 A berry. Slratiotes. 



Vallisneriacece. Aquatic herbs. Dioecious, diclinous. Staminiferous ; Flowers 

 in a spadix, from which they finally separate. Corolla monopetalous. Pistillift- 

 rous ; Spathe 1-flowered. Peduncles spiral. Calyx 1-leafed. Corolla poly- 

 petalous. Capsules 1 -celled, many-seeded. Seeds parietal. VaUisneria. 



Geography. Natives of Europe, North America, and the East Indies. One 

 species is found in Egypt (Ottelia indica), and two Vallisnerias in New Hol- 

 land. 



