'Olive tree' in the Bible

And if some of the branches have been broken off, and thou, a wild olive, hast been grafted in among them, and become a partaker with them of the root and fatness of the olivetree,

For if thou hast been cut off from an olivetree wild by nature, and hast against thy nature been ingrafted into a good olivetree, how much more shall these, the natural branches, be ingrafted into their own olivestock?