Whitewood comes from Wyld trees to my knowledge. Obviously could find one on a druid while in the Xadaron stronghold or on Archdruid Xadaron. Or harvest some wood from the tree while exploring the place, (but probably would need a druid to make it into a bow and they might not be happy) though maybe it's been tainted with fungus. I think Leorah the shopkeeper in Hawkethorne has one over her fireplace. I am sure a great quest or sex scene with her might win it also if someone could come up with one.a second way to get the whitewood bow besides defeating hethia