Jotham told them a parable/fable.
Greek fables used the animal kingdom, but Hebrew fables and parables used the vegetable kingdom. Although this is called a parable, it is more accurately a fable. it is only one if two fables in the Bible. The other is in 2 Kings 14:9-10 and another account of the same incident is in 2 Chronicles 25:18-19.
A fable is a short story in which animals or objects speak a story, to teach a moral or religious lesson. A parable is a short story designed to teach a moral or religious lesson. eg. The parable of the unforgiving servant. Matt 18:21-30. An allegory is a story in which ideas are symbolized as people. eg. Gal 4:24 The bible contains examples of all of these.
In this instance Jotham spoke of the olive, the fig, the vine, the bramble and the cedar. This was in keeping with the Hebrew literature in using members of the vegetable kingdom to teach a moral and a religious lesson.
Judges 9:7-15
The first tree was the olive. Olive oil was used for food and cooking, lighting, sacrificial offerings, ointment and anointing oil.
the “Olive Tree” is symbolic of a righteous person. Ps 52:8 It is the emblem of sovereignty. 1 Sam 10:1, 1 Kings 1:39, 2 Kings 9:1-6. Olive oil was used in the anointing and coronation of Kings. Olive oil is also symbolic of the anointing of the Holy Spirit i.e. God appointed and ordained Prophets, Priests and the fullness of time Kings and ministers of the Gospel. Sometimes also for the setting aside of specific ministries. Zech. 4:14 Joshua and Zerubbabel, the civil and religious leaders of the returned captives were symbolized as two olive tress vs.11. vs.14 Zechariah was told that they were the “two anointed ones who stood beside the Lord of the whole earth”
They were the vehicles through whom the religious/spiritual and civil/governmental blessings were conveyed.
Ultimately though these blessings are conveyed through the Lord Jesus Christ. Jesus is God’s olive tree. Rom. 11:11-24. We are grafted into Jesus. The Holy Spirit is His oil. Acts 10:38 The word anoint implies oil. Jesus was beaten and crushed so the oil would flow out. “It is to your advantage that I go away; for if I do not go away, the Helper will not come to you: but if I depart, I will send Him to you” Jn16:7.
Gethsemane is a place of many olive trees even to this day. And the name Gethsemane means “Olive Press”.