Olivetree - (Easton's Bible Dictionary)
Is frequently mentioned in Scripture. The dove from the ark brought an olive-branch to Noah (Gen. 8:11). It is mentioned among the most notable trees of Palestine, where it was cultivated long before the time of the Hebrews (Deut. 6:11; 8:8). It is mentioned in the first Old Testament parable, that of Jotham (Judg. 9:9), and is named among the blessings of the "good land," and is at the present day the one characteristic tree of Palestine. The oldest olive-trees in the country are those which are enclosed in the Garden of Gethsemane. It is referred to as an emblem of prosperity and beauty and religious privilege (Ps. 52:8; Jer. 11:16; Hos. 14:6). The two "witnesses" mentioned in Rev. 11:4 are spoken of as "two olive trees standing before the God of the earth." (Comp. Zech. 4:3, 11-14.)
The "olive-tree, wild by nature" (Rom. 11:24), is the shoot or cutting of the good olive-tree which, left ungrafted, grows up to be a "wild olive." In Rom. 11:17 Paul refers to the practice of grafting shoots of the wild olive into a "good" olive which has become unfruitful. By such a process the sap of the good olive, by pervading the branch which is "graffed in," makes it a good branch, bearing good olives. Thus the Gentiles, being a "wild olive," but now "graffed in," yield fruit, but only through the sap of the tree into which they have been graffed. This is a process "contrary to nature" (11:24).