The development of roots on a stem while the stem is still attached to the parent plant is called layering. A layer is the rooted stem following detachment (removal) from the parent plant.
Some plants propagate naturally by layering, but sometimes plant propagators assist the process. Layering is enhanced by wounding the stem where the roots are to form. The rooting medium should always provide aeration and a constant supply of moisture. The methods of layering can be broadly divided into ground layering and air layering.