I.

Introduction

Grafting, joining the cut surfaces of plants under circumstances that will allow physiological union. The supporting plant is called the stock; the plant part that is grafted to it is called the scion. The scion may be a twig, stem, bud, or other part of a plant; grafting in which the scion used is a bud is called budding. The ability of the cut surface to heal is dependent on intimate contact between the cambium layers of the scion and the stock. The cambium layer, a ring of reproductive tissue around the stem, produces callus tissue; this tissue is composed of large, undifferentiated cells. Callus tissue, in a successful graft, differentiates to form food-conducting vessels, water-conducting vessels, and a cambium layer, which connect the corresponding tissues of scion and stock.

Grafting is frequently used to combine advantageous characteristics of scion and stock. For example, branches or buds of trees known to produce good fruit are grafted to stronger trees that produce fruit of indifferent quality. Grafting is also used in propagating seedless fruits, such as seedless oranges and grapes.