104 VARIOUS FOOD-PLANTS 
Fig. 112.—Garden rhubarb (Rheum Rhaponticum, Buckwheat Family, 
Polygonacee). Plant in flower, x 2. (Vilmorin.)—A perennial herb; 
leaf-stalks often red; flowers whitish; fruit brown and dry. 
rich red tint and are ready for market. As will be seen from 
the chart, cacao possesses a very high nutritive value. 
Starch in the particularly palatable forms known as sago 
and tapioca, is obtained from certain tropical plants which are 
especially rich in this form of food. The best sago comes 
principally from the spineless sago-palm, shown in Fig. 116. 
When full grown the tree is felled and the trunk cut into 
sections to facilitate the removal of the spongy pith-like 
interior, which is gorged with starch. By repeated washings 
the starch is separated from the indigestible material, and 
is then finally dried and granulated into small pearl-like 
masses for the market. A single tree will yield from four 
hundred to six hundred pounds of sago. 
Tapioca is manufactured chiefly from the large fleshy roots 
of the bitter cassava (Fig. 117). Curiously enough the starch 
in these roots is associated with a milky juice which is de- 
cidedly poisonous. The poison, however, is of such a nature 
that it entirely disappears in the process of preparation. 
