of a monastery in Bahia, Brazil, probably yielded the first navel orange between 1810 and 1820. Nevertheless, a researcher at the University of California, Riverside, has suggested that the parent variety was more likely the Portuguese navel orange (Umbigo), described by Antoine Risso and Pierre Antoine Poiteau in their book Histoire naturelle des orangers ("Natural History of Orange Trees", 1818–1822). The mutation caused the orange to develop a second fruit at its base, opposite the stem, embedded within the peel of the primary orange. Navel oranges were introduced in Australia in 1824 and in Florida in 1835. In 1873, Eliza Tibbets planted two cuttings of the original tree in Riverside, California, where the fruit became known as "Washington". This cultivar was very successful, and rapidly spread to other countries. Because the mutation left the fruit seedless, therefore sterile, the only method to cultivate navel oranges was to graft cuttings onto other varieties of citrus trees. The California Citrus State Historic Park and the Orcutt Ranch Horticulture Center preserve the history of navel oranges in Riverside. Today, navel oranges continue to be propagated through cutting and grafting. This does not allow for the usual selective breeding methodologies, and so all navel oranges can be considered fruits from that single, nearly 200-year-old tree: they have exactly the same genetic make-up as the original tree and are clones. This case is similar to that of the common yellow seedless banana, the Cavendish, or that of the Granny Smith apple. On rare occasions, however, further mutations can lead to new varieties. Cara cara Cara cara oranges (also called "red navel") are a type of navel orange grown mainly in Venezuela, South Africa and in California's San Joaquin Valley. They are sweet and comparatively low in acid, with a bright orange rind similar to that of other navels, but their flesh is distinctively pinkish red. It is believed that they have originated as a cross between the Washington navel and the Brazilian Bahia navel, and they were discovered at the Hacienda Cara Cara in Valencia, Venezuela, in 1976. South African cara caras are ready for market in early August, while Venezuelan fruits arrive in October and Californian fruits in late November. Other Navels Bahianinha or Bahia Dream Navel Late Navel Washington or California Navel Blood Blood oranges are a natural mutation of C. sinensis, although today the majority of them are hybrids. High concentrations of