690 



SYSTEMATIC BOTANY. 



Cocoes, or Eddoes. C. himalensis has also edible corms. They are used for 

 food in the Himalayas. C. antiquorum is applied to a like purpose in Egypt, 

 and the corms of C. macrorhiza are eaten in the South Sea Islands under the 

 name of Tara. 



Natural Order 276. Pistiace^e or Lemnace^. — The Duck- 

 weed Order (^figs. 1068, 1069). — Floating aquatic plants 

 {fig. 236), with lenticular or lobed leaves or fronds. Flowers 

 2 or 3, enclosed in a spathe {fig. 1068), monoecious, placed 



Fig, 1068. 



I'-TiniLc^ai 



Fig. 1068. A moncecious head of flowers of a species of Duckweed (Lemna 

 minor), consisting of two male flowers, each of which is composed of a 

 solitary stamen with quadrilocular anthers; and one pistillate flower in the 



centre. The whole surrounded by a spathe Fig. 1069. Vertical section 



of the pistil of the same. 



on the margin or surface of the frond (fig. 236), or in the axils 

 of leaves. Perianth none, Male fiovoer with 1 {fig. 1068), or 

 a few stamens, which are often monadelphous. Female flower 

 consisting of a 1-celled ovary {fig. 1069), with 1 or more erect 

 ovules. Fruit 1- or more seeded, membranous or baccate, inde- 

 hiscent, or sometimes dehiscent. Embryo straight, cleft, in the 

 axis of fleshy albumen. 



Distribution, 8fc. — They inhabit cool, temperate, and tropical 

 regions. Examples : — Lemna, Pistia, Ambrosinia. There are 

 9 genera, and 20 species. Their properties are unimportant. 



Natural Order 277. Nai adages. — The Pond weed Order. 

 {figs. 1070 — 1073). — Aquatic plants with jointed cellular 

 stems. Leaves with interpetiolar membranous stipules. Flowers 

 small, unisexual {figs. 1070, 1071), Perianth either want- 

 ing, or composed of 2 or 4 parts. Stamens few, hypogynous ; 

 pollen globose. Ovaries 1 or more, superior {fig. 1071) j ovule 

 sohtary {fig. 1072). Fruit 1-celled, 1-seeded {fig. 1073). Seed 

 exalbuminous {fig. 1073) ; embryo with a lateral cleft. 



