What makes the navel on a navel orange?

Navel oranges don’t have seeds but they do have what looks a lot like a person’s navel or belly button.   This growth is actually another orange.  A mutation in the navel orange causes a small “twin” orange to grow opposite its stem.

Without seeds the only way to create more navel orange trees is to graft sprouted navel orange buds onto another tree’s trunk or roots.  Since they all come one original tree, navels are clones or genetic copies of each other. The most popular type of navel orange is the Washington Navel (otherwise know as Bahia or Riverside Navel).  Washington Navel oranges can all trace their heritage back to a single tree in planted at a monastery not far from Salvador, Bahia in Brazil.

The story goes that a Presbyterian missionary and his wife came across the original navel orange tree while visiting the monastery in 1820. They started several other trees from its buds. William Saunders at the U.S. Department of Agriculture heard about these oranges and arranged to get a shipment of 12 trees in 1870. He started growing them in a greenhouse on the mall in Washington, D.C. and later shipped hundreds of plants to Florida and California but they never grew.

Eliza Tibbets a former neighbor and friend of William Saunders asked if she could have some of the trees to grow at her new home in Riverside, California.  He sent her a few for her garden in 1873.  The climate was perfect for the oranges and Eliza took excellent care of them. California orange growers took notice of Eliza's flourishing navel orange trees and took buds from them to grow their own. These navel oranges eventually became popular around the world. One of Eliza Tibbets’ original navel orange trees is still growing and producing fruit today.

Incidentally, Brazil is the world largest producer of oranges.