It's true that many of the 'English' walnut trees in California & Oregon are grafts of thin-shelled Juglans Regia shoots onto Black Walnut Juglans Nigra root stock. This is mentioned in nursery catalogs as being quite desirable for better nut production, and SDH in one of his books mentions encountering a grafted example in the butt of one of his custom stocks.
Regards, Joe

You can lead a man to logic but you can't make him think. NRA Life since 1976. God bless America!