INTRODUCTION 17 



In underground stems, e.g. a rhizome or root- 

 stock, the leaves are scaly, and adventitious roots 

 form at the nodes. The main axis may be entirely 

 underground, or become partly aerial at length. If 

 in the last case the rhizome is broken away a new 

 plant forms. Suckers are developed on stems and 

 roots of shrubs and trees, and when adventitious 

 roots form and the suckers are separated from the 

 parent plant they form new plants. 



Tubers, corms, bulbs are shortened shoots or 

 enlarged stem bases which divide, and on separation 

 give rise to fresh plants, the new corms^ etc., being 

 formed below the old ones, or above, or laterally. On 

 leaves buds may form along the margin and develop 

 roots, as in the Cuckoo flower, etc., and give rise to 

 new plants. 



By artificial means it is possible to reproduce 

 plants by cuttings, either part of a root, stem, or leaf. 

 The best method is to select a shoot, broken just 

 below a node, from which, when struck, adventitious 

 roots are given off. In trees a part of the original 

 stem, or heel, is usually included. 



In the case of layers a shoot is bent down and 

 pegged into the soil by a U-shaped peg inverted like a 

 croquet hoop. The shoot is half nicked or cut 

 below, and roots develop from the half-severed part. 

 Finally the layer is completely isolated, and a new 

 plant is formed in this way. (See Fig. 5.) 



Other methods of artificial propagation are budding 

 and grafting. In the former case a bud is selected 



VOL. III. 2 



