PLANT PROPAGATION 39 



Every true bud is capable of forming a new plant like its 

 parent. When a branch containing buds has formed roots and 

 is cut off from the parent stem, a new plant has been produced. 

 The roots are formed from adventitious growth, which takes 

 place in the growing layer (cambium) which lies just beneath 

 the bark. Adventitious growth may also take place aboveground. 

 In this case sprouts form. Sweet-potato slips, the roots of cut- 

 tings and layers, the sprouts of old tree stumps, and the water 

 sprouts that form on the trunk and large branches of trees (par- 

 ticularly following heavy pruning) are all from dormant buds, or 

 of adventitious origin. It is known that cutting or wounding a 



FIG. 20. Strawberry plants started by runners 

 The runners develop new plants at the nodes, or joints 



plant stimulates the enzymes into activity, and it is probable that 

 these substances are responsible for causing the formation of 

 adventitious buds. 



44. Layers, runners, and root tips. A layer is a piece of 

 a plant, usually a branch, that has been partly covered with soil 

 to induce it to take root. Many woody plants with branches 

 long enough to reach to the ground can be propagated in this 

 manner; among those most frequently layered are grapevines, 

 ornamental shrubbery, honeysuckles, and climbing roses. To 

 propagate plants by layering, a branch should be covered deeply 

 enough to bring it in contact with moist soil. Layered plants 

 root better if the part of the branch that is to be covered with 

 earth is wounded by twisting, hacking, or scraping, for adventi- 

 tious growth is stimulated by such wounds. 



