Small citrus tree originally coming from Japan. The mandarin orange is a variety of the orange family. The mandarin cultivar "Clementine" sometimes is known as the "Christmas orange." The exterior is a deep orange colour with a smooth, glossy appearance and the can be separated into edible 7- 14 segments.
http://en.wikipedia.org/wiki/Clementine
References
http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/plant-finder/plant-details/kc/d389/citrus-reticulata-clementine.aspx
http://en.wikipedia.org/wiki/Clementine