An orange is a fruit of various citrus species in the family Rutaceae (see list of plants known as orange); it primarily refers to Citrus sinensis, which is also called sweet orange, to distinguish it from the related Citrus sinensis, referred to as bitter orange. The sweet orange reproduces asexually (apomixis through nucellar embryony); varieties of sweet orange arise through mutations.
The orange is a hybrid between pomelo (Citrus maxima) and mandarin (Citrus reticulata).