Herb to Know: Clove

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• Syzygium aromaticum
• (Sih-ZIJ-ee-um ah-ro-MAT-ih-kum)
• Family Myrtaceae
• Tree

How would pumpkin pie or spice cake taste without cloves, that pungent and most aromatic of spices? Those little brown sticks (“clove” comes from the Latin clavus, “nail”) that stud the Easter ham and holiday pomanders are actually the unopened flower buds of a tropical tree related to allspice and guavas.

The genus Syzygium, to which the clove tree belongs, comprises about 500 species of trees or shrubs native to the Old World Tropics. S. aromaticum itself is native to the Moluccas (Spice Islands), part of modern Indonesia. It is an evergreen tree growing about 40 feet tall with smooth gray bark and 5-inch-long, glossy opposite leaves that resemble bay leaves. The 1/4-inch flowers in clusters at the ends of the branches have four tiny petals surrounded by a long, four-parted calyx (the “stem” of the clove) and numerous stamens. The buds are pink, but the calyx changes from yellow to deep red-pink after the stamens fall. The fruit, called mother-of-cloves, is an edible purple berry about 1 inch long and 1/2 inch across. The entire plant is ­aromatic.

The generic name, Syzygium, comes from a Greek word meaning “yoked together” and refers to the union, in some species, of the petal tips into a cap that covers the stamens. The meaning of the specific name, aromaticum, is obvious.

Cloves were known at least 2,000 years ago in China. They are believed to have been brought by Javanese envoys to the Chinese court, where the emperor decreed that every visitor hold a clove in his mouth when addressing him. Arab traders introduced cloves into Europe by the fourth century A.D., and the Portuguese were trading for cloves in the Moluccas by 1511. Although clove trees grew on many islands in the Moluccas, the Dutch set out to control the clove trade in the seventeenth century by destroying all trees except those on a single island, which they controlled. In 1625 alone, 65,000 clove trees were cut down. The Dutch held the monopoly on cloves for about 150 years. During this period, any unauthorized person caught growing or carrying cloves or seedlings might be put to death. Finally, the French smuggled seedling clove trees to Mauritius, an island east of Africa in the Indian Ocean, and by 1800, clove trees were being cultivated on a number of islands in the Indian Ocean and in the New World. They are now grown commercially in Madagascar, Tanzania, Jamaica, Sri Lanka, Malaysia, Indonesia, Réunion, the Seychelles, and the Comoro Islands. Zanzibar and Pemba, islands off the east coast of Africa that are part of Tanzania, produce about 90 percent of the world’s cloves.

Growing Clove

Clove trees require a warm, humid climate with 50 to 70 inches of rainfall annually and a minimum temperature of 59°F; well-drained, fertile loam; and a position in full sun or part shade. Most clove ­plantations are located within 10° of the equator and close to the ocean. Commercial growers shade the young trees and protect them from wind, sometimes growing them under other trees such as mangos or jacarandas. Trees may be propagated by sowing seeds in spring or rooting semiripe cuttings in summer. Trees flower for the first time when eight or nine years old. The unopened flower buds are harvested by hand when they reach full size and are just turning pink. In Indonesia, women and children pick the clusters closest to the ground, while men either clamber into the branches or climb ladders to gather the higher clusters. Later, the buds are snapped off the flower stalks and placed on leaf mats to dry in the sun. After three days, they will have turned dark brown and weigh only one-third of their weight when first picked.

A tree may yield as much as 75 pounds of dried cloves, but the crop fluctuates from year to year. Under favorable conditions, trees may live 100 years or longer, but in Zanzibar, many have been killed by a devastating fungal disease called sudden death. Fortunately, young trees are apparently resistant to the disease.

General Uses For Clove

At least half the world’s clove supply goes into the manufacture of Indonesian cigarettes, and Indonesia, where cloves originated, is a major importer of the spice. Of the remainder, only those of the highest quality are used as a culinary spice. The rest, along with the dried flower stalks and leaves, are processed to extract the essential oil, which is used not only to flavor foods, but also in cosmetics, dentistry, medicine, and as a clearing agent in microscopy. About 85 percent of the oil is eugenol, which is also a component of the essential oils of cinnamon, bay laurel, basil, nutmeg, and hyssop, among other familiar herbs and spices.

As for the cloves that don’t go into making Indonesian cigarettes or clove oil, they can enhance so many kinds of food: fruits, baked goods, ham, beets, green beans, winter squash, pea soup. They’re also an essential ingredient of Chinese five-spice powder, Indian garam masalas, American mixed pickling spice, and spiced teas. The flavor of most ground spices fades rapidly, but that of ground cloves seems to last for ages. Use a light hand when seasoning with cloves: one or two whole cloves stuck in an onion simmered slowly in a stew, 1/4 teaspoon of ground cloves in a recipe for spice cookies.

Medicinal Uses For Clove

Practitioners of traditional Chinese medicine have used cloves to treat indigestion, diarrhea, hernia, hiccups, kidney disorders, intestinal parasites, fungal infections such as athlete’s foot, even impotence. Europeans have drunk clove tea mainly as a digestive aid, but during the Middle Ages, cloves were considered an aphrodisiac, perhaps due to the perceived similarity in shape of a clove and the human penis.

Clove oil has long been a home remedy for toothache. It relieves pain by desensitizing pain receptors in the tooth and combats inflammation by inhibiting the synthesis of prostaglandins. It is also antiseptic: dentists utilize the disinfectant property of its principal constituent, eugenol, mixed with zinc oxide as a temporary filling in root canal treatment, and a laboratory study showed that its constituents kaempferol and myricetin strongly inhibited the growth of bacteria associated with tooth and gum disease.

Other laboratory studies have confirmed that eugenol inhibits the growth of fungi including Candida albicans, the organism that causes human yeast infections. Animal studies have shown that it is also a strong antioxidant and protects against cardiovascular disease by preventing the aggregation of platelets.

Aside from using clove oil as an emergency toothache treatment, don’t try self-treatment with the oil or its constituents. They can be toxic in small amounts when taken internally or absorbed through the skin.


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