For the CG plane. With a name like "Arborea" (arbor "tree"), "tree people" makes sense.
This can be the Greekesque Dryad, Hamadryad, or something more plantlike, Treant or 4e Wilder. Or something similar.
A species that is a living plant (G), but is highly individualistic (C), might include both the possibility of like a human as a living statue of wood with hair of leaves, all the way to a pure animated tree, like a Treant. And anything in between. For a playable species, players choice.
Personally, I would rather the "furries" of GCG Beastland, also include human-looking with subtle animalistic features, as well as fully animal forms, and anything in between, including humanimal "furries". To some degree, Beastland already is this way.