The Fruit Museums

Your typical curator looks after a museum, a library or a zoo. Tracy Kahn takes care of 865 varieties of citrus--the world’s most comprehensive collection--at UC Riverside.

In her office, Kahn’s a picture of scientific seriousness, but walk with her through the 24-acre grove nearby and she grins and gushes over her exotic accessions: Buddha’s Hand citron, resembling a lemon crossed with an octopus; Australian finger lime, an olive-colored, oblong fruit filled with tiny spherical vesicles that look like citrus caviar; and variegated Valencia, a regular orange that happens to be swathed in stripes. And don’t get her started about the yuzuquat hybrid or the flying dragon tree, a thorny vision out of an ancient Chinese scroll.

Many of these specimens amaze the taste buds as well as the eye. Kara and Encore mandarins are spicy, rich-flavored tangerines developed by the university’s breeders from parents in the collection. (The grove is closed to the public, alas, but a citrus tasting including many unusual varieties from the collection will be held Saturday and Sunday as part of the Orange Blossom Days celebration in downtown Riverside.)

Other trees are valued only as rootstock. Kahn’s colleague, Ottillia Bier, a veteran of many fruit evaluations, shudders as she passes certain unpalatable fruits, such as the giant ultra-sour Cuban shaddock. “You couldn’t pay me enough to taste that again,” she jokes.

The great value of the collection is its diversity. Some day the genes of some bizarre specimen may prove invaluable to plant breeders searching for desirable traits such as productivity or pest resistance.

The Riverside collection, established in 1909, is one of the dozens of federal, state and private facilities that preserve an amazing cornucopia of fruits, nuts, vegetables and grains in orchards, fields, greenhouses and storage units around the country.

California’s other most spectacularly diverse “fruit zoo” is the National Clonal Germplasm Repository at Davis. The name sounds intimidating, but “clonal” refers to plant varieties and “germplasm” means genetic information in seeds and stems, from which new plants can be grown.

The Davis field collection, at the Wolfskill Experimental Orchard in nearby Winters, includes olives, figs, pistachios, pomegranates and stone fruits (peaches, plums, cherries, etc.). Just after dawn one day last summer, the curator, Charles Simon, drove around the 74-acre property, leased from the University of California, pointing out some of the most promising examples: small tan Pakistani apricots, twice as sweet as American varieties, which may impart better flavor to future hybrids; nearly shell-free walnuts from China; and cold-hardy wild grapes native to Texas. At times the collection seemed like an alternative universe, with red kiwis, white apricots and blue persimmons.

Just as zookeepers pamper rare animals, fruit curators struggle to keep their charges alive and healthy. As he inspected the rows of stone fruit, Simon, who became director in June, admitted that this section needed work. For years, he explained, most of the trees had been grown in pots in screened greenhouses, to protect against disease-bearing insects. In the early 1990s, alas, heat and other stresses killed many precious specimens.

“This year we’ll be planting out a lot of stone fruit,” he vowed. “By nature, they’re trees and don’t like being treated like potted plants; they need to get out in the field, where they’re happy. Also, we can’t get meaningful evaluation from a 2-foot-high bush.”

Supplementing state and federal institutions, private collectors play a critical role in rescuing and preserving unusual varieties. Many belong to California Rare Fruit Growers, an organization of fruit enthusiasts who gather to trade plants and expertise. It’s not uncommon to find members who have 60 cherry varieties or 100 figs or 300 passion fruits.

Three years ago, San Francisco attorney C. Todd Kennedy, who may well be California’s most knowledgeable fruit connoisseur, donated 50 rare and antique peach and nectarine varieties to the Davis repository, and these were just a few of the more than 2,000 fruit varieties at his orchard south of San Jose.

Kennedy’s studious old-world bearing is in keeping with his zeal for heirloom varieties, intensely flavored old favorites such as the luscious Lord Napier white nectarine, which once was an aristocratic “indulgence” but long ago lost favor with commercial growers.

Typically he’ll begin a discourse on fruit by declaring, “Most Americans have never tasted a really fine grape [or peach or plum].” When curators want the real lowdown on fruit, they call Kennedy.

The largest public collection, the National Germplasm system, originated in 1898, when botanical explorer David Fairchild founded the U.S. Department of Agriculture’s Section of Seed and Plant Introduction, which promoted the development of new varieties of such crops as dates, soybeans and avocados.

In the early years, researchers received most materials directly from explorers. Collections were maintained haphazardly until the establishment of four regional plant introduction centers in the late 1940s and the National Seed Storage Laboratory in 1958.

The current system dates from 1974, but the clonal collections of fruits and nuts really burgeoned in the 1980s as scientists recognized the vital importance of biodiversity to agriculture. Today 25 national repositories contain more than 436,000 genetically distinct accessions.

Each facility cares for species suitable in its climate. At Geneva, N.Y., curator Philip Forsline supervises 3,700 apple trees, ranging from the indigenous Prairie crab, tiny and astringent, to the Court Pendu Plat, a venerable French dessert apple of dazzlingly complex flavor.

On a blustery morning last autumn, Forsline showed off a prized row of specimens he’d gathered in Kazakhstan, the center of origin for most apples. “It was mind-boggling--large, smooth-skinned apples growing wild in the Tarbagatai Mountains,” recalled the soft-spoken curator, nibbling on an intriguing example that tasted of hazelnuts and bananas. All the apples usually available in America, he noted, come from a very narrow genetic base, leaving them vulnerable to pests and diseases.

In four expeditions from 1989 to 1996, he and his colleagues braved hair-raising helicopter rides over rugged slopes to bring back apples with natural resistance to scab and fire blight, two major problems for American growers. The quest to preserve this genetic treasure is urgent: Habitat destruction and economic turmoil threaten native varieties in Central Asia, where local farmers now favor Red and Golden Delicious.

Seed for grains and vegetables can be stored for long periods as long as they’re regrown at regular intervals--sown and harvested to refresh them. Most fruit and nut varieties, however, must be preserved as living plants, because seedlings are not identical to their parents. Since the mid-1980s, a less expensive alternative, cryopreservation, has emerged. Some plant tissues, such as apple budwood (the part of the stem that is used for grafting), can be stored indefinitely in a state of suspended animation, in plastic tubes above liquid nitrogen, at minus 196 degrees Celsius. Within three years, the entire clonal apple collection will be backed up in this way.

Scientists at the repositories try to record observations of their plants, such as growing habit, bloom date and resistance to disease, to guide researchers looking for specific traits. A database (on the Internet at https://www.ars-grin.gov/npgs) lists all accessions by number, scientific names, location and source, though further characterization is often scanty.

The Geneva Web site recently posted photographs of 50 typical apples, with flowers, stems and leaves as well as fruits; other repositories plan to do the same for their crops. In the long run, researchers hope to use gene mapping to identify varieties, eliminate duplication and speed development of new hybrids.

At most public collections, however, years of flat funding and declining purchasing power have left curators struggling to keep their plants alive. This parsimony infuriates Anne Marie Ruff, an energetic 27-year-old who once worked at the National Germplasm repository at Riverside, which cohabits with the Citrus Variety Collection.

In May 1997, she founded the American Genetic Resources Alliance, an informal coalition of academics, agriculture businesspeople, gardeners and environmentalists, to support a budget increase for the germplasm system. Over a recent sushi dinner, she lamented, “It’s ironic that at a time when biotechnology is most powerful, the material for it is most jeopardized. Many repositories are turning into seed morgues.”

By law, Federal employees--be they museum directors or seed collectors--can’t lobby Congress. But recently an industry group, the American Seed Trade Assn., hired a consultant in Washington in an effort to boost the current germplasm budget of $22.6 million to $40 million by 2002. Administrators at the Department of Agriculture are sympathetic, but the outcome of budget negotiations is unclear. As bureaucrats deliberate, America’s agricultural heritage hangs in the balance.

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The Orange Blossom Festival includes tasting from UC Riverside Citrus Variety Collection, 10 a.m. to 8 p.m. Saturday and 10 a.m. to 7 p.m. Sunday , Mission Inn Avenue and Orange Street, Riverside. Information: (909) 715-3400.