University of California, Riverside Citrus Variety Collection, Citrus variety collection in Riverside, California, United States

The University of California Riverside Citrus Variety Collection holds around 1,800 trees representing 640 different citrus types and related plant species for ongoing research. The site is organized like a living library where scientists study how these varieties perform and respond to different growing conditions.

The collection began in 1907 as the UC Citrus Experiment Station and quickly became a center for improving citrus growing methods. Over the decades, more than 40 new varieties were developed here, and scientists worked to find ways to fight agricultural diseases.

The collection reflects California's deep connection to citrus farming and remains important to the region's agricultural identity. Walking through it, you notice how the different varieties tell a story about what has mattered to local farmers for generations.

The collection is on the UC Riverside campus, with the original 1917 Citrus Experiment Station building in the Box Springs Mountain foothills; the site lies at 33°58′32″N 117°19′52″W. Two further plots of about 2 acres each are at the South Coast Research and Extension Center in Irvine and the Coachella Valley Agricultural Research Station in Thermal. As an active research facility, arrange visits ahead through UCR extension staff.

Curator Tracy Kahn regularly hosts chefs, farmers and fruit growers interested in rare varieties. Her collaborations with local chef Clements Brien of restaurant Omakase produced citrus tasting dinners that drew attention in New York and led to an invitation to cook a citrus meal for the James Beard Foundation.