The orange is a fruit of various citrus species in the family Rutaceae, primarily the cultivar Citrus × sinensis, also known as the sweet orange to distinguish it from C. × aurantium, the bitter orange. The sweet orange is a hybrid between the pomelo (C. maxima) and the mandarin (C. reticulata), with the pomelo being the chloroplast genome and maternal line. The orange originated in a region encompassing south China, northeast India, and Myanmar, and the earliest mention of the sweet orange found in Chinese literature dates from 314 BC. The sweet orange reproduces asexually (apomixis through nucellar embryony); varieties of sweet orange arise through mutations. The whole genome has been sequenced. This photograph, depicting a whole orange, a halved orange, and a peeled orange segment, was focus-stacked from eleven images.Photograph credit: Ivar Leidus