Complex sentence: The native distribution of the species is the southeastern United States, Mexico, Honduras, and the Caribbean, but it has apparently been distributed northwards in the United States by Native Americans who carried the plant with them as a food source.
Split into simpler sentences: The native distribution of the species is the southeastern United States, Mexico, Honduras, and the Caribbean. It has apparently been distributed northwards in the United States by Native Americans who carried the plant with them as a food source.