Floris and Blancheflour is the name of a popular romantic story that was told in the Middle Ages in many different vernacular languages and versions. It first appears in Europe around 1160 in "aristocratic" French. Roughly between the period 1200 and 1350 it was one of the most popular of all the romantic plots.
The following synopsis is from the original Old French "aristocratic" version (Floire et Blancheflor) of the late 12th century.
The Middle English version of the poem derives from an Old French "aristocratic" version but differs somewhat in details. The opening section concerning how the two are born is missing from the English versions. Originally it dates to around 1250 and was called Floris and Blanchefleur.
Felix, King of Al-Andalus (Muslim Spain), on one of his ventures into Galicia in northwestern Spain attacks a band of Christian pilgrims en route on the Way of St James to the famous medieval pilgrimage shrine of Santiago de Compostela. Among the pilgrims are a French knight and his recently widowed daughter, who has chosen to dedicate the rest of her life to the sanctuary. The knight is killed, and his daughter is taken prisoner to Naples, where she is made lady-in-waiting to Felix's wife. Both women are pregnant, and the children are born on the same day, Palm Sunday: Floris to the Muslim Queen, and Blanchefleur to her lady-in-waiting.
Floris ("belonging to the flower") and Blanchefleur ("white flower") are raised together at the court and grow close. King Felix fears his son may desire to marry the "pagan" girl and decides that she must be killed. However, he cannot bring himself to do the act and instead sends Floris away to school, then sells Blanchefleur to merchants traveling on the way to Cairo (called Babylon in the story), where she is then sold to the emir. Felix constructs an elaborate tomb for Blanchefleur and tells Floris she has died. Floris's reaction is so severe that Felix tells him the truth. Distraught but encouraged she is still alive, Floris sets out to find her.