Definition - What does Scion mean?
The scion is the upper part of the plant used during the grafting process, a viticulture technique that joins two parts, the scion to the lower part or root stock. The scion part of this combination grafting is going to be the part that produces more growth. Usually, a vine is selected for its grapes, stems or leaves and combined with another grapevine that has valuable roots.
WineFrog explains Scion
When a scion is joined with a stock (or rootstock), the plant that follows will be a stronger version of the original varietal or made into a hybrid version. This is most often seen in commercial winemaking, when the viticulturist wants to reproduce positive characteristics present on one vine’s leaves, stems or berries with another vine’s valuable root traits. Grafting does take time and the type of scion selected can vary, for example dormant buds can be the scion grafted onto another stem. The scion and rootstock joint will never be as strong but after a few weeks, if the vascular tissue has connected, it will survive and just have a weak spot.