Most everyone is aware of the usefulness of citrus as ornamentals and for fruit production; but 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 Succoth, 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 orange and kumquat (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 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, the sweet oranges are what most 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 limited space. The catalogue for the nursery I worked at near San Martin features more than forty. Some of the more esoteric were limequats, which are hybrids of limes and kumquats, and tangelos, which are hybrids of grapefruits and mandarins.

Two citrus which 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 which died and permitted to grow. Unfortunately, both can be frustrating to a garden enthusiast who is not familiar 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.