SOLANACEiE 



563 



becomes spreading later. It is smooth and generally solid. 

 It has no ribs at first, but as it develops, it becomes more or 

 less quadrangular. 

 Leaves. — Potato leaves are compound pinnate, with more 



Fig. 231. — Flowering branch of potato (Solanum tuberosum). 



or less petioled leaflets. The petiole bears a number of 

 supplementary leaflets which vary in number and importance 

 with the age of the plant. The rachis is decurrent (Fig. 12) 

 on the stem. The leaflets are oval, acuminate, and the base 

 heart-shape or oblique in shape. The leaves as well as the 

 stems are characterized by a narcotic smell. At the begin- 



