Tree
In general, trees represent the deepest and most significant intellectual concepts: the ones that come to us most directly from the Lord. This varies depending on us and our states: the people of the Most Ancient Church, who were in a state of loving the Lord, understood truth automatically and internally through what the Writings call "perception"; people in lower states (including most of us) have to work a little harder to learn it from the Word and by willing to follow the Lord. In other parts of the Bible, especially in the prophets and New Testament parables, the meaning of "tree" is broader, meaning not just a person's intellectual concepts but the whole person.
'Trees,' as in Joel 1:10-12, signify knowledges.
Psalms 50:2-5
2
Out of Zion, the perfection of beauty, God shines forth.
3
Our God comes, and does not keep silent. A fire devours before him. It is very stormy around him.
4
He calls to the heavens above, to the earth, that he may judge his people:
5
"Gather my saints together to me, those who have made a covenant with me by sacrifice."