694 



SYSTEMATIC BOTANY. 



Ariscema atrorubens. Dragon-root, Indian Turnip. — From the tuber of 

 this plant a nutritious fecnla is obtained in the United States. The tuber is 

 also given internally as a stimulant in rheumatism, bronchial affections, 

 &c., and is likewise used extensively as an application to aphthous affections 

 in children. 



Arum.—Th.Q underground stems (tubers or corms) of some of the species 

 of this genus contain a large quantity of starch ; those of A. maculatum, 

 Wake-Robin, Cuckow-pint, or Lords and Ladies, a common native of this 

 country, are the source of what has been called Portland Sago, or Arrow- 

 root ; 1 peck of tubers yields about 3 lbs. of starch. The preparation of this 

 starch is now, in a commercial point of view, given up. Formerly the tubers 

 were used medicinally as diuretics and expectorants. When fresh, they act 

 as an in-itant poison. A. campanulatum ot AmorphoiJhallus campanulatus, 

 and A. indicum, produce edible corms. 



Caladium bicolor.— The corms of this and other species, when cooked, are 

 edible. They are sometimes, but improperly, called " Yams " in tropical 

 countries. (See Dioscorea.) 



Colocasia.—C. esculenta and others have large fleshy corms, which are 

 much used in the West Indies, Madeira, &c., as food, under the names of 

 Yams (see Caladium bicolor), Cocoes, or Eddoes. C. himalensix 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. macroi'hiza are also 

 eaten in the South Sea Islands under the name of Tara. 



Natural Order 276. Pistiaceje or Lemnace^. — The Duckweed 

 Order {figs. 1069 and 1070). — Character. — Floating aquatic 

 plants {fig. 226), with lenticular or lobed leaves or fronds. Flowers 

 2 or 3, enclosed in a spathe {fig. 1069), monoecious, placed on 



Fig. 1069. 



Fig. 1070. 



Fig. 1069. A monojcious 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. 1070. Vertical 



section of the pistil of the same. 



the margin or surface of the frond {fig. 226), or in the axils of 

 leaves. Perianth none. Male flower with 1 {fig. 1069)^ or a 

 few stamens, which are often monadelphous. Female flower 

 consisting of a 1-celled ovary {fig. 1070), with 1 or more erect 

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



