See BFDI wiki for detailed canon info.
Tree was one of the 30 recommended characters in BFDI. In spite of that, he failed to join the show twice having the second least amount of likes in both turns.
In Reveal Novum, Tree got only 3 votes to join the show which is smaller than 1% of the votes and is certainly not enough to join the show.
In Yeah Who I Wanna Know?, Tree was yet present again but fails to join with only 49 votes having the second least amount of votes to join.
Tree reappears in IDFB in which, he does not play a major role in (until the next episode).
Tree's former appearance has a bushier top and his body is longer, revealing the roots making it look more realistic than the current one.
This was changed in IDFB, as Tree had the same bushier top, but with leaves shown shaded in light-green color, whereas his stem is no longer shows the roots (which is pretty illogical, despite the fact that plants cannot live without roots). There's also a little branch attached to his stem and on top of his "hair". He also gains his limbs.
- He is the only contestant in BFB to be voiced by Thomas Chick.