Love at First Bite: How Riverside Created the Perfect Valentine's Day Fruit

Holidays are often associated with iconic plants. Christmastime includes an abundance of holly and poinsettia. Pumpkins do double-duty for Halloween and Thanksgiving. What would the Day of the Dead be without marigolds?

Not so for Valentine's Day (yet). Shoe-horning red roses or chocolate-covered strawberries would be a stretch. Ideally, a plant for Valentine's Day should have certain characteristics that make it fit the holiday the way that the glass slipper matched Cinderella's foot. Clearly, a red heart should be a prominent feature. If edible, the fruit of the plant should be sweet, but a bit tangy, and complex. Finally, the season of the plant must correlate with the middle of February, but not extend months before or beyond that.

Remarkably, such a plant exists, and it was created in Riverside. The fruit of the citrus variety, 'Valentine', checks all the boxes. The yellow, grapefruit-size fruit matures on and around Valentine's Day; its season runs from mid-January to mid-March. Cut it open lengthwise and turn it upside down; you get the 'Valentine' surprise, deep red flesh in the shape of a heart. The soft red pulp is juicy and sweet, with a hint of acid. The overall flavor is complex and mysterious, yet familiar. 'Valentine' promises to become the iconic Valentine's Day fruit.

Now for the 'Valentine' story: How did this variety come to be? What twists and turns brought it to the commercial market? Fortunately, I can turn to my own Valentine of more than forty years, Dr. Tracy Kahn, for help. Not only is Tracy a citrus expert, but we were once featured as UCR's "Valentine's Couple" in Fiat Lux magazine. Tracy is the Curator of UCR's Givaudan Citrus Variety Collection (UCRGCVC), a living archive of trees representing over eleven hundred different types of citrus and citrus relatives, including 'Valentine'. The UCRGCVC is arguably the most diverse collection of its kind in the world. Tracy pointed me to two resources, an article on the commercial release of the variety (Siebert et al. 2009*) and the person who spearheaded that release, UCRGCVC Senior Museum Scientist Toni Siebert Wooldridge.

Like many "new" varieties, the story of 'Valentine' is not at all straightforward. The article Tracy provided me lays out the first part of the story. In the 1950's the citrus breeders at UCR, Dr. Robert Soost and Dr. James Cameron, decided to study the genetic basis of high versus low acidity in citrus by making a number of crosses. Several crosses involved the low acid pummelo, 'Siamese Sweet', as the seed parent. What we know now as 'Valentine' was the result of one of those crosses with a hybrid as pollen parent: 'Ruby' blood orange X 'Dancy' mandarin. The result was a tree bearing fruit with the low acidity and large size of the pummelo parent, the color, juiciness, and hint of raspberry flavor of blood orange, and the complex floral taste of mandarin. Because of its mid-February maturity and heart-shaped red flesh, Staff Research Associate Ottilie "Toots" Bier informally named it "Valentine" in the 1990's.

The distinctive fruits were shown to growers and the public as early as 1990. People found it fascinating. Staff of UCRGCVC formally evaluated the fruit from trees in Riverside as well as those at UC's Lindcove Research and Extension Center near Exeter (at the Sierra foothills of the San Joaquin Valley) in 2006, 2007, and 2008. The fruit quality was essentially identical for those different environments.

Much of the rest of the story comes from the "institutional memory" of Toni Siebert Wooldridge. The tipping point was mid-February 2008. Here's how Toni explains her original motivation for pursuing the release of the variety from the University, starting with reference to UCRGCVC's Assistant Specialist David Karp:

"At the time, David had brought fruit from UCR to the Santa Monica Farmers Market, where it caught the attention of Armando Garcia of Garcia Organic Farm in De Luz (Fallbrook). David gave Armando a few fruits to take home. Armando's father, Juan Garcia … at Durling Nursery … later contacted the Riverside County Extension Office and spoke with Tom Shea about the fruit, trying to learn more about how he could obtain the material. Tom Shea then called me to get additional information.

Around that same time, I had just returned from the Tulare Farm Show (a.k.a. World Ag Expo) and was fielding a growing number of inquiries about how to obtain the fruit which was typically displayed for the show. Tom Spellman of Dave Wilson Nursery was particularly interested. It became clear that interest in the variety was building rapidly.

By that point, I felt there was enough momentum to make a strong case for its release. We already knew the variety was exceptional from years of tours, displays, and tastings. It has always been very well received … I was growing increasingly frustrated with having to tell people that it wasn't available and that I didn't know if or when it ever would be. I wanted to change that.

Tracy and I spoke with Mike Roose, … and he explained what steps would be required to move forward with releasing 'Valentine'. He indicated that he did not wish to play a major role in its formal release. As a result, it became clear that we would need to take the lead on this effort."

Presently, you can find 'Valentine' pummelo fruits now, but not for long, at specialty groceries and farmers' markets. But they will only be around for a month at best.

Our Valentine story reveals three lessons about science and its application to the betterment of life: First, science's contributions to society often involve serendipity. In this case, the original cross was not intended for creating the ideal Valentine's Day fruit. The motivation was basic understanding of inheritance. Second, it may take a LONG time from an initial discovery to be realized as a benefit. Roughly half a century passed from the day that Soost and Cameron made their cross until the variety was released to the public. Finally, big changes are often the result of the efforts of one (or a few) people. I often hear folks say "When is the University going to decide to do X?" But the University doesn't decide anything. If not for Toni Siebert motivating the steps to release "Valentine', this holiday would remain fruitless.

• Siebert, T., O. Bier, D. Karp, G. Vidalakis, and T. Kahn. 2009. 'Valentine' a recently release anthocyanin-pigmented pummelo hybrid developed at the University of California Riverside. Topics in Subtropics 7:3 2-5.

Thanks to Amy López for inspiring the topic of this article. Interviews with Toni Siebert Wooldridge and Tracy Kahn filled in key components of the story.