254 



coloured 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. Butomese are 

 most closely akin to Alismacese. M. Decandolle has a remark (Syst. 2. 42.), 

 that no Endogense are lactescent; but Limnocharis yields milk in abund- 

 ance. This genus offers a singular example of a large conspicuous open 

 hole in the apex of its leaf, apparently destined 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. HYDROCHARIDE^. The Frog-bit Tribe. 



Hydrocharides, Jtiss. Gen. 67. (1789) Hydrocharide.e, Dec. Fl. Fr. S. 265. 



(1815) ; R. Brmun Prodr. 344. (1810) ; Richard in Mim. Mus. vol. 1. 3G5. (1815); 

 Agardh Aph. 127. (1822); Lindleifs Synopsis, 254. (1829) — VALLisvERiACEii; 

 and Stratiote^, Link Handb. 1. 281. (1829.) 



Diagnosis. Tripetaloideous monocotyledons, with an inferior ovarium, 

 and exalbuminous antitropous embryo. Water plants. 

 Anomalies. 



Essential Character. — Flmvers hermaphrodite or unisexual. Sepals 3, herba- 

 ceous. Petals 3, petaloid. Stamens definite or indefinite. Ovary single, inferior, 1- or 

 many-celled; stigmas ^-G ; ovules indefinite, often parietal. Fruit dry or succulent, in- 

 dehiscent, with 1 or more cells. Seeds without albumen ; embryo undivided, antitropous. 

 Floating plants. Leaves with parallel veins, sometimes spiny. Flowers spathaceous. 



Affinities. These water-plants are readily distinguished from all 

 other monocotyledons by their tripetaloideous flowers, with an inferior ova- 

 rium; by this they are separated from Alismacese, with which they agree 

 in habit and want of albumen, but from which they also diifer, as Pomaceaj 

 from Ranunculacese, in the carpella being definite, not indefinite. Comme- 

 lineae are at once recognised by their superior trilocular ovarium. Agardh 

 refers here Trapa (see p. 58.); Linnaeus placed Hydrocharidese along with 

 Palms ! in his natural arrangement. 



Link defines his Hydrocharideae, Stratioteaj, and Vallisneriacese, thus; — 



Hydrocharidea. Aquatic herbs. Leaves with parallel veins connected 

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

 polypetalous. Pericarpium. Albumen none, unless the thickened part of 

 the embryo. Hydrocharis. 



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

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

 A berry. Stratiotes. 



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

 in a spadix, from which they finally separate. Corolla raonopetalous. Fe- 

 males; Spathe 1-flowered. Peduncles spiral. Calyx 1-lcafed. Corolla 

 polypetalous. Capsules 1 -celled, many-seeded. Seeds parietal. Vallis- 

 neria. 



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

 One species is found in Egypt (Ottelia indica), and two Vullisnerias in New 

 Holland. 



