In grafting, what happens to the two different plant parts?

In grafting, the two different plant parts, known as the scion (the upper part) and the rootstock (the lower part), undergo a process where they heal together and establish a union. This successful union allows the vascular systems of both parts to connect, enabling the transfer of nutrients and water. As a result, they grow as a single entity, creating a new plant that possesses characteristics from both the scion and the rootstock. This union is critical for the grafted plant to thrive and is utilized in horticulture to combine desirable traits, such as disease resistance and fruit quality.

The other options do not accurately describe the fundamental purpose and outcome of grafting—where the goal is to unify two distinct plant tissues to foster growth and establish a viable plant rather than seeing them die together or grow independently. Creating a new species is also not a result of grafting, as the grafted plant remains within the same species or variety of the original plants.