Both resulted from a hybrid between the trifoliate orange and the Washington navel orange. The area is fairly dry and requires irrigation to supply the navel orange groves. Ray looked at the orange and saw the printed word "Navel" for navel orange. The citrus industry in California had begun before Tibbets' introduction of the Washington navel orange. The mutation gives the navel orange no seeds. The navel orange is a mutation of regular sweet orange. The trees thrived in the southern California climate and the navel orange industry grew rapidly. The Washington Navel Orange is also called California Navel Orange. Early Brazilian publications often referred to the Navel orange, or "lavanja de ombigo". The industry developed from the country's first navel orange trees, planted in Riverside in 1873. The navel orange was not new when Tibbets introduced it to United States agriculture. By 1917 Washington navel orange culture was a $30 million per year industry in California.