VEGETABLE FOODS 



157 



times extracted and used in coloring butter; it is also a source of 

 vitamin C. Carrots, like turnips, were introduced into Virginia 

 and New England by the first English colonists. 



The PARSNIP comes from species still found wild in the 

 Mediterranean region, where it has been cultivated since the days 

 of the Romans. In a parsnip root the food storage region is found 

 in a cortex and phloem proportionately larger even than that 

 of the carrot (fig. 93). The small xylem zone is of little impor- 

 tance. Escaped parsnip plants, as in the case of the carrot, have 

 established themselves as weeds in waste places. 



CORTEX CAMBIUM 



Fig. 92. — ^The cortex and 

 phloem of a carrot root is 

 much larger than that of the 

 raddish or turnip. 



CORTEX CAMBIUM 



Fig. 93. — In a parsnip the 

 food region occurs in the cortex 

 and phloem. 



The SWEET POTATO is the American contribution to our stock 

 of root vegetables. It is not found today in the wild state, but all 

 of its related species are tropical American in distribution, so that 

 the sweet potato is assumed to be a new world plant. Sweet 

 potatoes were the plants that were first known as "potatoes"; 

 it was much later that the term was applied to the edible tuber 

 which since has become more widely known. Sweet potatoes 

 were first recorded from Cuba and other islands of the West 

 Indies, to which they had probably been transported from 

 Central America. They belong in the same genus as the familiar 

 morning glory, and have similar flowers and a comparable trail- 

 ing habit. The thickened root has most of the food stored in the 

 central xylem zone, as in the radish (fig. 94). Being of tropical 



