A number of species roses and early hybrids produce roots that are much more vigorous and productive than a large number of Hybrid Teas. To give Hybrid Teas that were to be sold as bare-root plants an advantage, breeders began attaching canes of the Hybrid Tea they were producing to root-stock from a species or early hybrid. The joint is called the graft and the rose is said to be grafted. There is a price to be paid, however. If the root-stock is virus infected, then the grafted rose will be as well. This is, unfortunately, too common a problem. And if the root stock has a tendency to sucker, then roses of a sort very different from the kind thought to be planted begin springing up. In the case of roses that are not cold-hardy, as is the case with many Old Roses, a plant grown on its own roots has a chance of regenerating itself from the roots after the top-growth has been killed by a frost, not so with grafted roses. It is also said that own-root roses tend to outlive grafted ones. How true this might be, I'm uncertain. Austin tells of a Hybrid Tea on Rugosa Roots that is over 75 years old.

vegetative propagation referring to the joining of two pieces of living tissue (scion and rootstock)

Propagation technique where a cut stem of a plant is attached the rootstock of another. The tissues of the stems grow together.

A sheet is said to be grafted when it has an ancestor sheet that is a graft.