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TEXTBOOK OF BOTANY 



dormant period is completed, the tops of the young sprouts may enlarge 

 and become tubers instead of growing into upright green shoots. The 

 same eflFect is produced if the sprouts are repeatedly remo\'ed from 

 tubers stored for several months ( Fig. 185 ) . 



Fig. 185. Growth of potato sprouts. A, apical dominance; B, apical dominance 

 is annulled when the tuber is cut into several pieces which are planted separately; 

 C, apical dominance partially annulled and vigor of sprouts decreased by storage 

 at high temperatures (33-34° C.) for a year; D, repeated removal of sprouts on 

 tubers in storage results in the growth of sprout tubers. A-C from C. O. Apple- 

 man; D from J. Bushnell. 



Corms and bulbs. The corms of gladiolus and crocus, and the bulbs 

 of onion and tulip are examples of other types of vegetative propagules 

 common to many herbaceous plants. These organs develop annually from 

 lateral buds, and when mature they become separated from the parent 

 plant (Fig. 186A). Like tubers, thev usuallv live through parts of two 



Fig. 186. Vegetative multiplication of wild garlic by bulbs: A, roots and base 

 of flowering shoot from old bulb and three new bulbs which have developed from 

 lateral buds; B, clusters of small bulbs, or "sets," in the flowering heads of aerial 

 shoots. Vegetative multiplication by these small bulbs is so effective that garlic 

 often becomes abundant in pastures. Courtesy of World Book Co. 



