The bronze plaque tells the tale: "The most valuable fruit introduction yet made by the United States Department of Agriculture."
And there, at Magnolia and Arlington avenues in Riverside, stands the last of California's original Washington navel orange trees, enclosed by an iron fence, looming over the plaque in the summer sun.
It is the tree that launched the storied citrus industry in the Riverside area, an industry that helped shape the world's view of Southern California as a tropical paradise in the early 20th century.
It was not the first orange tree to grow in Southern California. But the Washington navels that were planted in Riverside did so well that they became the standard in the "citrus belt" that spanned the inland foothills.
Buds from the Riverside tree were used to plant other trees, which in turn spawned thousands of others.
"The Washington navel is the parent of the citrus industry in Southern California and Arizona," said Claire Smith, spokeswoman for Sunkist Growers Inc., the citrus cooperative. "It gave [growers] a winter orange to sell and the seedless variety, which proved successful."
The Washington navel ripens in winter. The orange is large, easy to peel and brilliant in color. The name comes from the protruding "navel" opposite the stem.
Because the oranges were packed in shipping crates with colorful labels showing the California landscape, the crates served as ads that attracted tourists and settlers.
Residents of other states, while fretting over the cold and the snow, would see the label on the orange crates and long for the California dream of sunny skies, warm weather and endless citrus groves.
"During subzero winter conditions, you have a piece of Southern California in your hands," said Vincent Moses, director of the Riverside Municipal Museum. "If you can't get to Italy, just take your Pullman [train] out to Southern California."
The Washington navel orange was brought to California by Eliza Tibbets, a woman known as a dreamer.
Tibbets was jobless and living in Washington, D.C., with her lawyer husband and children. The family lived next door to William Saunders, superintendent of gardens and grounds for the Department of Agriculture.
The Tibbetses moved to Riverside in the 1870s, and Eliza Tibbets asked Saunders to send her some orange trees, trees that he had requested from Brazil. He mailed her two small originals, which began producing fruit in 1875.
In 1902, they were moved to the corner of Magnolia and Arlington, where the living one remains. A year later, the other one was again moved, to the front of the historic Mission Inn, in what is now downtown Riverside. That tree died in 1921.
The one survivor was threatened with trunk rot caused by a fungus, but horticulturalists found a way to save it. Their experiment is still evident at the base of the trunk: They gave the tree a new root system so it would take nutrients from a different source, and eventually the tree outgrew its original roots.
While there were other successful types of oranges, much of Riverside and its environs became a navel orange empire. The parent trees spawned millions of offspring, Moses said, eventually covering Riverside and spreading to the San Gabriel Mountains and Corona in 20,000 acres of groves.
"Can you imagine what that would look like when they were blooming? It was like almost living in a perfume bottle," Moses said.
The lucrative crop led to the creation of the Southern California Fruit Exchange, which became the California Fruit Growers Exchange, and eventually Sunkist.
The cooperatives were formed so the growers and the pickers would have better working conditions and relations with the commercial packers, and better distribution in the markets. Moses said that by 1920, the Fruit Growers Exchange was averaging $100 million a year from the sale of citrus, which included the navel oranges.
"We were in effect the center of economic enterprise in much of the Inland Empire. It was big-time," Moses said.
California's major advantage over other states is that the climate allows the orange to ripen to a nice color, Smith said.
"They grow tons of oranges in Florida, but the fruit is not nearly as pretty," Smith said. "Most of their oranges go to processing, go to juice. Most of our oranges go to hands. We call it eating fresh."
Simone McFarland, marketing coordinator for the city of Riverside, said the Washington navel helped put the city on the map.
"The orange is a huge part of our heritage. It is what brought Riverside to what we are today," McFarland said.
For much of the first half of the 20th century, the orange was the dominant crop in Southern California. In addition to the inland citrus belt, oranges were grown in Orange County.
After World War II, the groves began to give way to suburban tract homes. Today, Southland acreage devoted to oranges is a tiny fraction of what it was. In the Riverside area, it has shrunk to perhaps 1,500 of the 20,000 acres cultivated at peak production -- and packinghouses in the region get most of their oranges from the Central Valley.
The image of the orange has also changed.
"Orange groves [have become] associated with 'rural hick town,' " Moses said. "It's no longer associated with the Hollywood California dream town."
But to those interested in California's citrus past, the site of the "parent tree" is hallowed ground.
"The oranges are what made Riverside so rich -- rich in money, rich in culture, rich in the vibrancy that we have today," McFarland said.