The presence of citrus in the medieval garden lacks any utilitarian sense since the old bitter trees didn’t produce edible fruits, cultivation obeyed almost exclusively to ornamental purposes. In this sense it is defining the quote from the historian and traveler of the fourteenth century Ibn Jaldun: citrus (along with lilo or cypress) are trees whose fruits contain no nourishment or use.
Ibn Jaldun was during a time ambassador of the Nasrid sultans of Granada. He went to Seville to meet King Pedro I of Castile and ratify a treaty of peace between the two kingdoms. During his visit, before being received by the king in the Hall of Ambassadors, Ibn Jaldun was likely to go through the Patio of the Maidens, where there were citrus planted and in which he could thus check the ornamental use of these trees in the palace. Past the Middle Ages, as there was progress through the hybridization of citrus, new species that produced edible fruits were generated.
Once edible citrus were achieved by hybridization they were incorporated into one of the main resources of the Alcázar, orchards, whose lease generated significant benefits. During the creation of the Huerta del Retiro, there was a change in the preference for bitter orange in the group of citrus, since in the project for the creation of this new garden, in 1911, included the recommendation that new orange trees are grafted with mandarin. From that date onwards we probably count with the presence of mandarin in the Real Alcázar.