of the Citrus × sinensis is considered a sweet orange, whereas the fruit of the Citrus × aurantium is considered a bitter orange . The sweet orange reproduces asexually ( apomixis through nucellar embryony ); varieties of sweet orange arise through mutations. [2] The orange is a hybrid , between pomelo ( Citrus maxima ) and mandarin ( Citrus reticulata ). It has genes that are ~25% pomelo and ~75% mandarin; [2] [3] however, it is not a simple backcrossed BC1 hybrid, but hybridized over multiple generations. [4] The chloroplast genes, and therefore the maternal line, seem to be pomelo. [2] The sweet orange has had its full genome sequenced. [2] Earlier estima