INTERRELATIONS BETWEEN PARTS OF PLANTS 399 



ancient times, a large number of methods for the artificial propa- 

 gation of plants have been in practical use. Artificial propa- 

 gation comprises methods that do not require the use of any 

 special organs of sexual or asexual reproduction formed by the 

 plant itself but that utilize any convenient and suitable vege- 

 tative parts. 



The most popular method of artificial propagation is by means 

 of cuttings and layers. By a ''cutting" is understood any part 

 of either the stem, the root, or even the 

 leaf of a plant, which, having been 

 separated from the plant and placed in 

 favorable conditions for its develop- 

 ment, is capable of growing. If such a 

 vegetative part is left organically con- 

 nected with its maternal tissues, though 

 only during the first stages of rooting 

 and growth, then it is called a ''layer." 

 Both of these methods are very popular 

 among fruitgrowers and gardeners. 

 Layering is used when cuttings do not 

 root readily, e.g., in the case of grapes, 

 hazelnuts, mulberries, gooseberries, etc. 

 In order to obtain a layer, a branch is 

 usually bent down and covered with soil 

 for some length, the tip being turned 

 upward and left uncovered. The 

 covered section in time will produce 

 adventitious roots, after which the 

 branch may be cut off and the layer separated from the maternal 

 plant (Fig. 121). Sometimes rooting does not occur under this 

 procedure. Then it is necessary either to make incisions on the 

 part of the branch that is covered with earth or to girdle it. A 

 callus is usually formed above the incision, or girdle, from which 

 roots will arise. 



Cuttings usually consist of sections of the stem, either with or 

 without leaves. Their lower ends are placed in soil or sand to 

 a certain depth. The soil used for this purpose must be very 

 loose, preferably sand, and the cuttings have to be placed in an 

 inclined position, so that their lower end is not too deep in the 

 soil. This is necessary because the healing of the wound caused 



Fig. 121. — S h o w i n g a 

 method of obtaining a layer 

 (6) from a grapevine {after 

 Molisch) . 



