These are the ones we buy at the supermarket and eat daily. They’re popular because they have such a long growing season. In the US, for example, they are readily available from November through April.
In 1917, a study was conducted which determined that a single mutation of a Selecta orange tree planted at a monastery near Bahia in Brazil in 1810 is what produced the first navel orange.
However, it’s also believed that the Portuguese navel orange was the tree from which the mutation occurred. Either way, because the mutation left the fruit seedless, the only way to grow more is by grafting cuttings onto other varieties of citrus trees. It was soon introduced in Australia and Florida, now about 180 years ago.
Navel oranges are actually still produced through cutting and grafting today, which means there is no possibility for selective breeding, and so navel oranges today have the exact same genetic makeup as the original two hundred years ago.