UMBELLIFER.E 541 



like rootstock, 2 to 4 inches long. These rootstocks con- 

 stitute the edible portion of the plant (Fig. 223). 



There are two general types of the common celery: (i) 

 self-blanching varieties — quick-growing, very tender, easily- 

 blanching sorts, especially adapted for fall and early winter 

 use (White Plume, Golden Self-blanching). Blanching (see 

 page 250) is secured by keeping the leaf stalks away from the 



Fig. 223. — Celeriac (Apium graveolens). (After Vilmorin.) 



Ught; the leaf blades, however, are permitted to grow in the 

 light, so that the processes of food-making proceed in a 

 normal manner, and the stalk is not stunted. Chlorophyll 

 is formed only in those parts of the plant exposed to the 

 light directly. Boards, paper or earth are placed about the 

 stalks to exclude the hght. 



(2) Green or winter varieties-r-not as quick-growing or 

 easily blanched as those of the preceding type and, further- 



