The Yew

"He's always been able to move, though he doesn't very often. He's quite slow. But that fence is a very useful thing. I don't want any of the children running around to eat his leaves or berries." Because yews are poisonous. The berries are technically edible, but the seeds inside the berries are not, making actually eating them tricky. "Or playing lumberjack or making him scared." Because if the yew has an excuse, it wouldn't hesitate before aggressively defending itself.