The orange is the fruit of the citrus species Citrus × sinensis in the family Rutaceae, native to China.[1] It is also called sweet orange, to distinguish it from the related Citrus × aurantium, referred to as bitter orange. The sweet orange reproduces asexually (apomixis through nucellar embryony); varieties of sweet orange arise through mutations.[2][3][4][5]

The orange is a hybrid between pomelo (Citrus maxima) and mandarin (Citrus reticulata).[2][6] The chloroplast genome, and therefore the maternal line, is that of pomelo.[7] The sweet orange has had its full genome sequenced.[2]