When I saw this it got me thinking along the lines of some sort of wooden Effigy Creature (CA 151) subjected to Awaken Construct (SC 21) maybe with levels of Warshaper or something like that. While I know Thurbane mentioned a plant race, it looked more carved to me than natural.
I even considered the novelty of a wooden Effigy Creature (Warforged) at one point.