sentences:  It was introduced into California commercial agriculture in 1914, though it was grown at the Citrus Research Center (now part of the University of California, Riverside) as early as 1909.Clementines lose their desirable seedless characteristic when they are cross-pollinated with other fruit.In 2006, to prevent this, growers such as Paramount Citrus in California threatened to sue local beekeepers to keep bees away from their crops.