THE SWEE:T potato. 73 



of the leaf-stalks, with perhaps occasional other 

 spots of purple. Still others have stems which are 

 for the most part purple, but shade into a dull 

 greenish-brown, and from that into green at the base 

 and tip and in various otlier places, so that while a 

 large portion of the stem is actually purple, the dull 

 greenish-brown color is also quite evident. Thin or 

 young stems are often entirely green. These stems 

 have been called ' ' greenish-brown to purple. ' ' Then 

 there are varieties in which the stems are unmis- 

 takably purple. It may be that even in these a few 

 inches at the base and tip are green, but there are 

 no entirely green young stems, and there is no green- 

 ish-brown color in evidence. These varieties are 

 termed "purple-stemmed." 



Almost as constant as the width of the leaves is 

 the thickness of the stems. In the '"thin-stemmed" 

 varieties the stems never measure more than one- 

 eighth inch in diameter; the diameter is determined 

 by lajdng the stem across a rule and looking with 

 one eje. The "thick-stemmed" varieties measure 

 at least three-sixteenths of an inch at the thickest 

 part of their full-grown stems, and some of them 

 even measure more than one-quarter inch. 



Another character, which can be seen at a glance, 

 is the purple star-shaped spot which some varieties 

 have on the upper surface of the leaves at the point 

 where the basal primary veins spring from the 

 petiole. This purple spot has been called the 

 "star." It may be present or absent. 



The lower surface of the midrib and the other 

 large veins affords another easy means of distin- 

 guishing between varieties. In some varieties the 

 lower surface of the primary veins is more or less 

 deeply colored purple. In others some of the older 



