102 



A TEXTBOOK OF BOTANY [Ch. Ill, 13 



(Fig. 62 a), having very characteristic forms and markings, 

 differing with the kind of plant (Fig. 63). Starch is 

 formed from sugar only in the plastids of the cells, either the 

 chloroplastids of the green cells, or the colorless leucoplastids 



Fig. 63. — Typical grains of various starches ; highly magnified. Upper 

 row, Potato, Maranta, Pea, Hyacinth; middle row, Wheat, Oats, Sago, 

 Smilax ; lower row, Canna, Corn, Bean, Oxalis. 



The characteristic forms and markings of the grains form invaluable 

 identification marks in the recognition of adulterations of foods, etc. (Re- 

 drawn from Ganong, The Living Plant.) 



of storage cells; and it cannot as yet be made artificially. 

 Starch is particularly abundant in tubers (Potato), tuberous 

 roots (Sweet Potato), bulbs (Lilies and Hyacinths), and es- 

 pecially in large seeds, to all of which its presence imparts a 

 dull, white, firm aspect, in marked contrast to the soft trans- 



