'Geheimrat Dr. Oldenburg' is a German applecultivar. It was created in 1897 at the Höheren Lehranstalt für Obstbau of Geisenheim in the Rheingau, in Hesse in central Germany.[1] It may also be known as 'Geheimrat Doktor Oldenburg', 'Geheimrat Oldenburg', or simply 'Oldenburg'. It is a quite different apple from the older Russian cultivar 'Duchess of Oldenburg', also sometimes known simply as 'Oldenburg'.
Cultivars that descend from 'Geheimrat Dr. Oldenburg' include: 'Alkmene' (Geheimrat Dr. Oldenburg × Cox's Orange Pippin); 'Apollo' (Cox's Orange Pippin × Geheimrat Dr. Oldenburg); 'Clivia' (Geheimrat Dr. Oldenburg × Cox's Orange Pippin);[4]: 539 ; 'Elektra' (Cox's Orange Pippin x Geheimrat Doktor Oldenburg); 'Roba' (Geheimrat Dr. Oldenburg x unknown);[2] and possibly 'Dukat' (Geheimrat Dr. Oldenburg × Cox's Orange Pippin).[4]: 538