The Citrus genus represents a large group of cultivated species, many of which are hybrids. The sweet orange is no exception. Although its genetic origin is obscure, sweet orange is thought to be a cross between pummelo and mandarin varieties.
One thing known for certain from ancient writings is that this species of orange has been cultivated for at least 4,000 years in China, India, and possibly southeastern Asia. Today it is grown commercially all over the world.
