48 THE SWEET POTATO. 



golden-yellow, bronze-colored, yellowisli-purple, light 

 or dark purple ; flesh, white, cream-colored, pinkish- 

 white, pinkish-orange, with or without purple marks ; 

 cambium and wood elements, white, dirty-white, yel- 

 low or orange, very distinct, or indistinct. 



Latex abundant or scanty. Flesh soft, so as to 

 cut very easily, or hard, so as to break better than 

 cut. 



Root (Microscopical) : In young root, xylem shows 

 five patches more or less separated by medullary 

 rays. In tuber, groups of xylem elements, or iso- 

 lated elements, each surrounded by actively dividing 

 area, scattered throughout the fundamental tissue. 

 Fundamental tissue and dividing tissue filled with 

 starch consisting almost entirely of compound 

 grains. Cambium with ring of xylem elements re- 

 mains near outside of tuber, with or without xylem 

 elements radiating towards center. Occasionally five 

 or more strands of xylem elements run along the 

 outer surface of the tuber, outside of the cambium, 

 forming the longitudinal ridges known as "veins." 

 These may or may not divide up and anastomose 

 profusely. 



(B) Stem (Macroscopical) : Variable in length, 

 from about two feet in some bunch varieties (Fig. 

 39) to 20 feet or more in those with running vines. 

 Variable in thickness, depending on the variety, 

 from Vs iiich to more than i/4 inch in diameter at 

 its largest part. 



Variable in habit, depending on the variety, 

 strongly twining or not at all, strongly running or 

 growing in a clump, prone to fasciation or not. 

 Variable in color; usually more or less purple col- 

 ored when emerging from the tuber; when grown, 

 light green throughout, or purple at the very base 



