Every part of the Yew tree
Taxus Baccata is deadly poisonous except for the berry (although the seed is pretty poisonous too if you crunch into it). This is a wise move given that the Yew depends on birds to disperse its seeds. It would be pretty foolish if the berry killed its seed transporter. The seed passes thought the birds GI tract undamaged and is deposited in a nice little bit of fertiliser.
