Photograph by Shari Kaplan
Grapefruits and their kin, including lemons, limes and tangelos, can range from sweet to sour. Most citrus are winter ripeners and are currently in season.
Citrus trees have many uses, from fruit to cultural rituals
By Tony Tomeo
Most everyone is aware of the usefulness of citrus as ornamentals and for fruit production, but many would be amazed by the range of other significant, ethnically specific functions. During Tet, the Vietnamese New Year celebration, kumquat trees with fruit are brought indoors for good luck. Chinese New Year has a similar tradition involving mandarin trees. A group of six fruited Rangpur lime trees has special importance in Hindu culture.
Perhaps my favorite tradition involving citrus is the significance of the Etrog citron in Judaic culture. During the season of Sukkot, a fruit from the citron, with the stem still attached, is nested in a "citron box" and displayed in the home. When I grew Etrog citron trees a few years ago, I learned that the trees must grow on their own roots, either from seed or cuttings. Fruit from grafted trees would not be kosher.
The most popular of citrus include sweet orange, lemon, lime, grapefruit and mandarin orange. Less common citrus include variations of these, as well as blood oranges and kumquats (which is actually of the genus Fortunella rather than Citrus.) Tangerines are actually the same as mandarin oranges, but have been developed in California. The name is applied to California mandarins, the same as "sparkling wine" is to a product otherwise known in France as champagne.
The variations of the more common citrus are distinguished by their acid content or flavor. For example, sweet oranges are what most people are familiar with for eating fresh, or juicing. Variations include sour oranges and bitter oranges.
Sour orange trees are useful as understock for standard (large) trees, or may grow into attractive ornamentals. The fruit of sour orange trees are used in marmalades. Bitter orange fruit is used in flavor extracts, fragrances and furniture polish. Bitter orange trees are the most exotic of ornamental citrus.
Other citrus variations include sweet lime, sour mandarin and a rare sweet lemon. The Rangpur lime is actually a sour mandarin.
There are many more cultivars of citrus than I can describe in this limited space. The catalogue for a nursery I worked at near San Martin features more than 40. Some of the more esoteric were limequats--hybrids of limes and kumquats, and tangelos--hybrids of grapefruits and tangerines.
Two citrus that often appear unintentionally in gardens are shaddock and a type of sour orange. The shaddock is the understock for most dwarf citrus. Conversely, the sour orange is the understock for most standard citrus. Either can sucker below the graft and overtake the scion above the graft.
More commonly, a citrus tree dies back to the ground. When new shoots appear, they are often assumed to be the same as the tree that died and are permitted to grow. Unfortunately, both can be frustrating to a garden enthusiast who is unfamiliar with their natural characteristics.
The shaddock grows into an awkwardly structured tree with wicked thorns. The fruit is extremely large with very thick, lumpy rind. Some think they are gigantic grapefruits or lemons. The flavor is either bland or sour. Because the fruit is so prolific and large, disposal can be a problem.
Sour oranges are more difficult to recognize as understock because they resemble sweet oranges. The trees are attractive, but usually taller than sweet oranges and produce long thorns. If mistaken for a sweet orange, considerable effort may be wasted in attempts to encourage production of sweet fruit. Fortunately, other cultivars of citrus are easily grafted onto sour oranges, as well as shaddock.
Tree of the week: grapefruit
My all-time favorite Citrus is the 'Marsh' grapefruit. It is likely the most common among older grapefruit trees, but also the reason many people do not like grapefruits. 'Marsh' grapefruits are large and pale yellow with a rich flavor too acidic for many citrus enthusiasts. "Oro Blanco" is the "other white grapefruit," which produces milder, but sweeter, fruit contained in a thick rind. Because it is more closely related to the pummelo, the membranes are easily separated from fruit segments.
Red and pink grapefruit are not as mildly flavored as the "Oro Blanco," but are sweeter. Red grapefruits will be sweeter in warmer climates, but do not perform as well and may not always be available in the Santa Clara Valley. Both reds and pinks are relatively weak and may take several years to produce fruit. As with most citrus, grapefruit ripens through winter and is currently in season.
Horticulturist Tony Tomeo can be contacted at 408.358.2574.
Saratoga, California Since 1955
