170 PEOPAGATION OF PLANTS. 



CHAPTEE XIII. 

 PEOPAGATING BY LAYERS. 



The same principles given for propagating plants b f 

 cuttings are applicable to layers, with this difference : 

 layers of the green and growing parts do not need to bi) 

 surrounded with a confined atmosphere, in order to pre- 

 vent a too rapid evaporation of their juices through the 

 leaves. A layer is only a cutting that is allowed to re- 

 main attached to the parent plant until it has produced 

 roots through which it may collect sustenance for self- 

 support. 



Various methods are employed to produce this result, 

 such as ringing, girdling, twisting, tonguing, or partly 

 dividing that portion of the stem or branch on which it 

 is desired that roots shall be formed. All these distor- 

 tions of the stem or branches of the plant layered are for 

 one object, that is, to check the downward flow of sap. 

 Eoots then become necessary for supplying sustenance to 

 the cutting, or layer, and are consequently formed. 

 The most common method of preparing layers is that of 

 making a tongue on the under side of the branch. The 

 operation is performed thus : Make an incision in the 

 branch or part of the plant to be layered, just below a 

 bud, cutting through the bark and into the branch to 

 the depth of one-quarter to one-half its diameter; then 

 pass the knife upward for an inch or more, according to 

 the size and nature of the plant being layered, splitting 

 the branch lengthways, forming the tongue as shown in 

 figure 64 at a. The branch is then bent down and 

 fastened in its place by means of a hooked peg, c, 

 and the end tied up to a stake, b, as shown in figure 

 64. That part on which the incision is made ia 

 covered with soil or other material that will exclude it 



