In grafting, the rootstock is the

• A. The underground portion of the grafted plant
• B. The shoot with dormant buds grafted onto a rootstock
• C. The cambial tissue between scion and rootstock
• D. The dried wax surrounding the graft

Answer: (A)

Rootstock is the part of the grafted plant that provides the roots and the below-ground support for the whole setup. In grafting, a scion—the desired above-ground shoot with its buds—is joined to the rootstock so their tissues heal together at the cambial layers and form a single plant. The rootstock determines the root system, vigor, and often drought tolerance or disease resistance, while the scion supplies the characteristics you want above ground, like fruit or flowers. The other descriptions refer to the scion itself, the tissue where the graft unions form, or protective wax, not to the rootstock.