The second part of this mame- Rigidoporus ulmarius comes from the fact the main host of this fungi was elm- Ulmus. It has now become less frequent due to the affects of Dutch Elm Disease.
I have seen it on Plane, horse chestnut and lime trees.
Rigidoporus is very similar in appearance to Perenniopora fraxinea. The difference is that the flesh is whitish and the tube layer is orange for Rigidoporus, whereas in Perenniopora the layers are a similar colour.
The bracket is perennial and causes a brown rot low down in the trunk.