The orange (specifically, the sweet orange) is the fruit of the citrus species Citrus × sinensis in the family Rutaceae. The fruit of the Citrus sinensis is considered a sweet orange, whereas the fruit of the Citrus aurantium is considered a bitter orange. The orange is a hybrid, possibly between pomelo (Citrus maxima) and mandarin (Citrus reticulata), which has been cultivated since ancient times.
Probably originating in Southeast Asia, oranges were already cultivated in China as far back as 2500 BC. Arabo-phone peoples popularized sour citrus and oranges in Europe. Spaniards introduced the sweet orange to the American continent in the mid-1500s.