A dryad is an oak tree nymph or oak tree spirit in Greek mythology; Drys means "tree", and more specifically "oak" in Greek. Today the term is often used to refer to tree nymphs in general.
The Dryad by Evelyn De Morgan
La dernière dryade (The Last Dryad) by Gabriel Guay, 1898.
In Greek mythology, Phoebe is the name or epithet of the following characters:
Dryad
…Some of the individual dryads or hamadryads are: Atlanteia and Phoebe, two of the many wives or concubines of Danaus Chrysopeleia…
Phoebe (right) witnesses her sister Helen (left) being abducted by Theseus and Pirithous (middle), Attic red-figure stamnos c. 430-420 BC. National Archaeological Museum, Greece.
Io changed into a cow, Mercury cuts of Argus's head