dryad

1. (Greek mythology) A female tree spirit.Examples: "There it had stood for years, close beside a mighty oak, under which sat often the kindly old priest, who told stories to the listening children. The young chestnut tree listened with them: the Dryad inside it, who was still a child, could remember the time when the tree was so small that it only reached a little higher than the ferns and long blades of grass."