The clove plant grows as a small, compact, evergreen bush, which thrives in warm, humid, climates. If allowed to flower, the plant produces a striking pink flower, which is then followed by purple berries.
Cloves are used in the cuisine of Asian, African, and the Near and Middle East countries, lending flavor to meats, curries, and marinades, as well as fruit such as apples, pears or rhubarb. Cloves may be used to give aromatic and flavor qualities to hot beverages, often combined with other ingredients such as lemon and sugar. They are a common element in spice blends such as pumpkin pie spice and speculoos spices.
The spice is used in a type of cigarette called kretek in Indonesia. Clove cigarettes have been smoked throughout Europe, Asia and the United States. Starting in 2009, clove cigarettes must be classified as cigars in the US.
hough long-used in traditional medicine, there is little evidence that clove oil containing eugenol is effective for toothache pain or other types of pain, although one review reported efficacy of eugenol combined with zinc oxide as an analgesic for alveolar osteitis. Studies to determine its effectiveness for fever reduction, as a mosquito repellent, and to prevent premature ejaculation have been inconclusive. It remains unproven whether using cloves or clove oil reduces blood sugar levels. Use of clove for any medicinal purpose has not been approved by the US Food and Drug Administration, and its use may cause adverse effects if taken orally by people with liver disease, blood clotting and immune system disorders, or food allergies.
Cloves are used in Indian Ayurvedic medicine, Chinese medicine, and western herbalism and dentistry where the essential oil is used as an anodyne(painkiller) for dental emergencies and various other disorders.The essential oil is used in aromatherapy.
In Chinese medicine, cloves or ding xiang are considered acrid, warm, and aromatic, entering the kidney, spleen and stomach meridians, and are notable in their ability to warm the middle, direct stomach qi downward, to treat hiccup and to fortify the kidney.
Eugenol composes 72–90% of the essential oil extracted from cloves and is the compound most responsible for clove aroma. 100% extraction occurs at 80 minutes in pressurized water of 125 °C. Ultrasound-assisted and microwave-assisted extraction methods provide more rapid extraction rates with lower energy costs.
Other important essential oil constituents of clove oil include acetyl eugenol, beta-caryophyllene and vanillin, crategolic acid, tannins such as bicornin, gallotannic acid, methyl salicylate (painkiller), the flavonoids eugenin, kaempferol, rhamnetin, and eugenitin, triterpenoids such as oleanolic acid, stigmasterol, and campesterol and several sesquiterpenes. Eugenol is toxic in relatively small quantities; for example, a dose of 5–10 ml has been reported as being a near fatal dose for a two-year-old child.