'Tree' in the Bible

Now if some of the branches have been broken out, and thou, being a wild olive tree, hast been grafted in amongst them, and hast become a fellow-partaker of the root and of the fatness of the olive tree,

For if thou hast been cut out of the olive tree wild by nature, and, contrary to nature, hast been grafted into the good olive tree, how much rather shall they, who are according to nature be grafted into their own olive tree?