CLASSIFICATION OF ANGIOSPERMS. 577 



which is known as CANAIGRE; the rhizome of Polygonum Bistorta 

 of Europe which yields the drug BISTORTA. 



Polygonum cuspidatum of the gardens contains emodin ; poly- 

 gonin, a glucoside yielding emodin ; and probably emodin methyl 

 ether. Rumex ecklonianus of South Africa contains emodin, a 

 volatile oil and a resin. The fatter consists of emodin monomethyl 

 ether; chrysophanic acid, physosterol (resembling rhamnol), etc. 

 Polygonum Hydropiper and P. aviculare, both common in the 

 United States, are poisonous to sheep. 



A number of the plants of this family yield food products. 

 Buckwheat is the fruit of Fagopyrum csculentum indigenous to 

 Central Asia and cultivated in many parts of the world (Fig. 292). 



Some are also cultivated as ornamental plants, as the Prince's 

 feather (Polygonum orientate). 



XI. ORDER CHENOPODIALES OR CENTROSPERM^E. 



This order includes seven families, in all of which the embryo 

 is curved or coiled, and the reserve consists chiefly of perisperm. 



a. CHENOPODIACE^: OR GOOSEFOOT FAMILY. 

 The plants are annual or perennial herbs with simple leaves and 

 small perfect flowers, the fruit being a utricle. The fruits of a 

 number of the group contain volatile oil, and are used in medi- 

 cine, as the common wormseed (Chenopodium ambrosioides 

 anthelminticum) , which is found in waste places in the United 

 States. Most of the oil is distilled in Maryland and is known in 

 commerce as " Baltimore oil." 



Chenopodium mexicanum yields saponin. Atriplex hortensis 

 of Tarfary yields indigo. The ash of very many species of Atriplex 

 as well as genera of the Chenopodiaceae yields soda. The seeds 

 of several species are edible, as of Chenopodium viride of Europe 

 and Asia, C. Quinoa of Chile, etc. Seeds of Spinacia tetandra 

 of the Orient are used in bread-making. 



A number of species are used as garden vegetables, as spinach 

 (Spinacia oleracea) and beet (Beta vulgaris). 



The SUGAR BEET (Beta vulgaris Rapa), which contains from 

 4 to 15 per cent, of cane sugar (sucrose), is largely cultivated in 

 Germany, as well as to some extent in the United States, and is 

 an important source of cane sugar. While the juice of the beet 



