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.

On a natural level, "clinging" to someone clearly indicates a desire to be close to them and conjoined with them. It often has a negative connotation – it's connected with emotional neediness and a bit of paranoia – but is a good thing in proper balance in a happy marriage, with each partner putting the other ahead of friends, family and other interests. When it is used in the Bible, "clinging" generally represents mutual love. This can be in marriage, in friendships or in a general state of loving others and wishing to serve them. At the deepest level, when the idea is of "clinging to Jehovah," it represents a desire to know and follow the Lord’s commandments so that we can be ever better and loving and serving others.