Many of the attributed Gorham lamps have been re-attributed to Amboy Works after the Reed & Barton archive was discovered. A few of these here have Gorham signed bases so have some claim to be Gorham.
The big florals on the tree / root bases are in need of more research into Gorham and will stay here until that happens.
The super complex traditional shade examples on signed Gorham bases are confidently attributed to Gorham. The first 3 examples below are typical of what we are describing here.