VEGETABLE FOODS 



155 



parts of many of our native wild plants are edible and have been 

 used by primitive Americans on many occasions. Our cultivated 

 root-crop plants, however, come from only four families; the Pig-^ 

 [weed Family contributes the beet; the 

 Mustard Family, the radish, turnip 

 and horseradish; the Parsley Family, 

 the parsnip and carrot; and the Morn- 

 ing Glory Family, the sweet potato. 



The present-day wild beet which 

 grows along the seacoasts of Mediter- 

 ranean Europe is considered the 

 ancestral type from which the culti- 

 vated varieties have arisen. By selec- 

 tion, plants with fleshier and larger 

 tap roots have been produced, in 

 which an abundant supply of carbo- 

 hydrates is stored (fig. 89). The garden 

 beet, at first, had the white roots 

 typical of most plants, but the red-fleshed varieties have become 

 more popular in the last few hundred years. In the beet root, 

 the food is stored in alternate zones of xylem and phloem pro- 



FiG. 89.— The fleshy tap 

 root of the beet contains a 

 supply of carbohydrates stored 

 in alternate zones of xylem 

 and .phloem. 



XYUM 



CAMBIUM 



Fig. 90.- 



PHLOCM 



-Unlike the beet, the turnip contains stored food almost entirely in the 

 xylem portion of the root. 



duced by successive cambiums, with resulting concentric rings 

 of growth similar to the annual rings of a tree. 



Turnips, like beets, are biennials forming swollen tap roots 

 the first year and blooming the second. Originally native to 



