Graft

The process of wound healing is absolutely necessary for successful grafting. Healing involves the cooperative production of new cells, some of which form cambium. From the cambium, new vascular (transport) tissues develop, permitting the transfer of water, nutrients, and hormones (growth regulators) to and from the scion. This interaction at the cellular level requires that the scion not be rejected by the stock. Hence, grafting is most likely to succeed with plants that are very closely related: either varieties of the same species, or members of the same genus. However, not all members of the same genus are compatible with each other. Sometimes the union can only be successful if one member is always the rootstock. For example, within the genus Prunus, peach scions cannot be grafted onto plum rootstocks, but plums can be grafted onto peach. Surprisingly, some pears (Pyrus species) can be grafted onto quince (Cydonia oblonga), despite the generic difference. Whether a particular combination is compatible can only be discovered by testing.