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.
Arcana Coelestia #749
749. 'Male and female' means truth and good. This is clear from what has been stated already at Chapter 6:19 where 'male and female' have reference to birds, but 'male and mate' 1 to beasts. The reason is also stated there, namely, that things of the will are married to those of the understanding, but less so those of the understanding regarded in themselves to those of the will. The former exist as male and mate 1 but the latter as male and female. Now because here the subject first of all is the temptation of that man as regards things of the understanding, as has been stated, the phrase 'male and female' is used, and conflict, or temptation as regards things of the understanding, is meant.
Footnotes:
1. literally, man and wife