In pokemon since all of the professors are named after trees, except for professor Rowan, is there a rare tree called a Rowan tree?
Rowan, also known as mountain ash, is a kind of ash tree. This tree was the tree of life in Nordic mythology and held all 9 worlds of the universe within the limbs and roots.
Well in Pokemon anything can happenSo yes he's probably named after a rare tree.
There is a rowan tree, which can also be classified as a shrub.http://en.wikipedia.org/wiki/Rowan