98 THE NURSERY-MANUAL 



Cuttings of tubers 



Tubers are thickened parts of either roots or stems (page 63), 

 and tuber-cuttings, therefore, fall logically under those divi- 

 sions; but they are so unlike ordinary 

 cuttings in form that a separate classifi- 

 cation is desirable. One form of tuber- 

 cutting is seen in Fig. 101. 



Tubers are stored with starch, which 

 supports or supplies the plant in time of 

 need. Tuber-cuttings, therefore, are able 

 to support themselves for a time if they 

 are placed in conditions suited to their 

 FIG. 101. Cuttings of a vegetation. Roots rarely arise from the 

 tubers themselves, but from the base of 

 the young shoots that spring from them. This fact is famil- 

 iarly illustrated in the cuttings of Irish and sweet potatoes. 

 The young sprouts can be removed and planted separately, 

 and others arise from the tuber to take their places. This 

 practice is employed sometimes with new or scarce vari- 

 eties of the Irish potato, and three or four crops of rooted 

 sprouts can be obtained from one tuber. The tuber is cut 

 in two lengthwise, and is then laid in damp moss or loose 

 earth with the cut surface down, and as soon as the sprouts 

 throw out roots sufficient for maintenance they are severed 

 and potted off. Sweet potatoes are usually propagated in this 

 way. 



In making tuber-cuttings, at least one eye or bud is left to 

 each piece, if eyes are present ; but in root-tubers, as the sweet 

 potato, there are no buds, and it is necessary only to leave on 

 each portion a piece of the epidermis from which adventitious 

 buds may develop. The pseudobulbs of some orchids are 

 treated in this way, or the whole bulb is preferably planted. 

 A shoot, usually termed an off-shoot, arises from each pseud o- 



