A 木霊, 木魂, or 木魅 (Kodama) is a spirit from Japanese folklore, which is believed to live in certain trees (similar to the Hamadryad of Greek myth). Cutting down a tree which houses a Kodama is thought to bring misfortune, and such trees are often marked with shimenawa (lengths of braided rice straw rope used for ritual purification in the Shinto religion.) rope.
Nice song, anyone know who sings it?
The word can also refer to an echo and they appear in もののけ姫 (Princess Mononoke) as little bobbleheads!
I kind of like the 人面樹 (Jinmenju or human-face tree) whose fruit resemble human faces. The faces are always smiling or laughing, even as they fall from their branch.
You will likely give up watching this half way through, don't say you weren't warned...
A 山霊 (Sanrei) is a mountain spirit that traps travellers who pass by it. I couldn't find much other info but from the looks of its Lost & Found Dept., people tend to disappear and leave their garments behind.
My final Killer 木 (Ki=tree) is my favourite Godzilla villain ビオランテ (and I know she isn't technically a tree but a mutated rose, work with me here.)
These don't have any trees but here is Week 2 of my JHS's Halloweeny pictures: