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.