For as long as her tree grows, the dryad will remain virtually ageless and physically unchanged. If for any reason that tree dies, then she too will soon wither like a flower and eventually die.
The dryad has been gifted with the ability to charm a mortal at a glance and will use this as her primary defense against those that seek to harm her or the tree she is sworn to defend. The dryad can also detect the presence of magic in any item she holds or touches as well as the presence of goodness in any item or individual.
The bond she shares with her tree allows her to protect herself in a defensive layer of barkskin and resist the effects of disease. Dryads, like all faeries, are resistant to the charming effects of creatures and magical spells of that nature.
The one true fear of a dryad is fire.