bark is a protective covering around the trunk of / branches of a tree
tree_bark is protective_system. bark is not hard_covering_for_tree. bark is covering. tree_bark is external_anatomical_part. tree_bark is not protective_system. tree_bark is plant_part. tree has not bark_around_outside_of tree has bark_around_outside_of bark is hard_covering_for_tree. tree_bark is not external_anatomical_part.