An orange specifically, the sweet orange is the citrus Citrus sinensis (Citrus Sinensis (L.) Osbeck) and its fruit. It is the most commonly grown tree fruit in the world. The orange is a hybrid of ancient cultivated origin, possibly between pomelo (Citrus maxima) and mandarin (Citrus reticulata). It is an evergreen flowering tree generally growing to 9-10 m in height (although very old specimens have reached 15 m). The leaves are arranged alternately, are ovate in shape with crenulate margins and are 4-10 cm long. The orange fruit is a hesperidium, a type of berry.