This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A sucker is an aerial shoot springing from an underground stem or root. Suckers usually have some fibrous roots attached to them, and when severed from the parent may be regarded almost as established plants. Such plants as Chrysanthemums, Plums, Black Currants, Raspberries, Blackberries, Loganberries, produce suckers freely, and may be propagated by them. In the case of Apples, Plums, Peaches, Nectarines, Roses, etc, any suckers arising are, of course, from the wild stocks, and are detached as early as possible, unless they are required later on to form stocks themselves.
Fig. 71. - Layering by Tongueing and Ringing.
Fig. 72. - Serpentine Layering.