what is grafting in plants

Grafting is a horticultural technique used to join parts from two or more plants so that they appear to grow as a single plant. In grafting, the upper part of one plant (scion) is joined to the lower part of another plant (rootstock) . The scion becomes the top of the plant, while the rootstock becomes the root system or part of it. Grafting is used for a variety of purposes, such as to change a large tree from an old to a new variety, to produce dwarf plants, to repair injured or diseased plants, to retain varietal characteristics, to adapt varieties to adverse soil or climatic conditions, to ensure pollination, and to propagate certain species that can be propagated in no other way. However, not all plants can be grafted, and generally, only plants closely related botanically form a good graft union. Incompatible grafts may not form a union, or the union may be weak, resulting in plants that are not healthy.