Fern Bumppo Root is the name given by Philip José Farmer in Doc Savage: His Apocalyptic Life to the wife of Gideon Root (mother of his daughter Esther Root), left unnamed by Ross Lockridge, Jr in his novel Raintree County.
In his book, Farmer claims to have located her gravestone, which states that her parents were John Bumppo and Juno Cooke.