In Romans 11:17, Gentile believers are pictured as a wild shoot of which tree, grafted in?

Answer: Olive

Some branches were broken off, and Gentiles, a wild olive shoot, were grafted in to share in the nourishment of the olive root.

“Now if some branches have been broken off, and you, a wild olive shoot, have been grafted in among the others to share in the nourishment of the olive root, do not boast over those branches. If you do, remember this: You do not support the root, but the root supports you.”— Romans 11:17-18 (BSB)