5 2 THE NURSERY-BOOK. 



Cuttings proper may be divided into four general classes : i, of 

 tubers ; 2, of roots and root-stocks ; 3, of stems ; 4, of leaves. 



i. Tuber Cuttings. Tubers are thickened portions of either 

 roots or stems, and tuber cuttings therefore fall logically under 

 classes 2 and 3 ; but they are so unlike ordinary cuttings that 

 a separate classification is desirable. Tubers are stored with 

 starch, which is designed to support or supply the plant in time 

 of need. Tuber cuttings are therefore able to support them- 

 selves for a time if they are placed in conditions suited to their 

 vegetation. Roots rarely arise from the tubers themselves, but 

 from the base of the young shoots which spring from them. 

 This fact is familiarly illustrated in the cuttings of Irish and 

 sweet potatoes. The young sprouts can be removed and planted 

 separately and others will arise from the tuber to take their 

 places. This practice is employed sometimes with new or scarce 

 varieties 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 to maintain them they are severed and potted 

 off. Sweet potatoes are nearly always propagated in this manner. 



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

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

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

 each portion a piece of the epidermis from which adventitious 

 buds may develop. The pseudo-bulbs of some orchids are 

 treated in this manner, or the whole bulb is sometimes planted. 

 A shoot, usually termed an off-shoot, arises from each pseudo- 

 bulb or each piece of it, and this is potted off as an independent 

 plant. (See Orchids, in Chapter VI.) 



Cuttings made from the ordinary stems of some tuberiferous 

 plants will produce tubers instead of plants. This is the case 

 sometimes with the potato. The cutting produces a small tuber 

 near its lower extremity, or sometimes in the axil of a leaf 

 above ground, and this tuber must be planted to secure a new 

 plant Leaf cuttings of some tuberiferous or bulbiferous plants 

 produce little tubers or bulbs in the same way. Hyacinth 



