Navel oranges are characterized by the growth of a second fruit at the apex, which protrudes slightly and resembles a human navel. They are primarily grown for human consumption for various reasons: their thicker skin makes them easy to peel, they are less juicy and their bitterness –a result of the high concentrations of limonin and other limonoids– renders them less suitable for juice. Their widespread distribution and long growing season have made navel oranges very popular.