CUTTINGS AND LAYERS 



21 



ally increased when the roots are broken, as by a plow. 

 Broken roots of apples often sprout. Plants may propa- 

 gate by means of root cuttings. 



54. The buds which appear on roots are unusual or 

 abnormal, they occur only occasionally and in no definite 

 order. Buds appearing in unusual places on any part of 

 the plant are called adventitious buds. Such are the buds 

 which arise when a large limb is cut off, and from which 

 suckers or watersprouts arise. 



55. LAYERS. Boots sometimes arise from aerial stems 

 that are partially buried. It' a branch touches the ground 

 and takes root, it is called a 

 layer. Gardeners often bend a 

 limb to the ground and cover it 

 for a short distance, and when 

 loots have formed on the cov- 

 ered part, the branch is severed 

 from its parent and an inde- 

 pendent plant is obtained. See 

 Pig. 29. 



."it;. There are several kinds of 

 layers: a creeper, when a trail- 

 ing shoot takes root throughout 

 its entire length; a runner, when 

 the shoot trails on the ground and takes root at the 

 joints, as the strawberry; a stolon, when a more or less 

 strong shoot bends over and takes root, as the black 

 raspberry or the dewberry (Pig. 29); an offset, when a 

 few verv strong plants form close about the base of the 

 parent, particularly in succulent or bulbous plants, as 

 house-leek (old -hen -and -chickens) and some lilies. The 

 rooting branches of the mangrove and banyan (Figs. 

 ].">, 17) in;i\ be likened to layers. 



57. natural CUTTINGS. Sometimes cuttings occur 

 without the aid of man. Some kinds of willows shed 



I, A layer of dewberry. Tlio 

 new plant )ia- arisen al 

 the left. 



