A tree of impossible size stands for something greater than you: family, history, ambition or life itself. Dream tradition reads it as awe, shelter or a challenge still to be climbed.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.