It is cultivated in Tanzania, Indonesia, Penang and to a lesser extent in the Seychelles, Reunion, Mauritius and Sri Lanka. In India, it is grown and cultivated in Tamilnadu and Kerala. It thrives in all situations ranging from the sea level up to an altitude of 900 m. But is unable to withstand long summers.

A large shrub or medium sized tree with pyramidal or conical crown 9-12 m. high and sometimes taller. The main stem is erect and often forking at a height of 1.5-1.8 m. The bark is smooth and grey. Leaves lanceolate, in pairs, acute at both ends, 7.5-12.3X 2.5-3.75 cm. in size, gland-dotted and fragrant. Flower buds borne in small clusters at the ends of branches, greenish, turning pink at the time of maturity and aromatic. Drupes (MOTHER-OF-CLOVE), fleshy, dark pink, 2.5 cm. long x 1.5 cm. thick. Seeds oblong, soft, grooved on one side and 1.5 cm. Iong.

Principal Constituents:

The cloves contain 13 per cent tannin (gallotannic acid). Oleanolic acid has been isolated from spent cloves (residue from the distillation of essential oil. Steam distillation of clove buds yields a colourless (14.23%) or pale-yellow oil, with the characteristic odour and taste of cloves. The oil darkens with age or on exposure and becomes reddish brown. The product obtained from whole buds contains a higher percentage (97%) of eugenol than that in oil distilled from crushed cloves (eugenol-94%). Water distillation yields oil of better quality and lower specific gravity (eugenol 85-89 %) than that obtained by dry steam-distillation (eugenol, 91-95%). The two oils are distinguished as 'opt' and 'strong' oils; commercial oil is a mixture of both. The clove bud oil contains free eugenol, eugenol acetate (2-17%) and caryophyllene (chiefly and ß-form) as its main constituents.Among the other constituents present, the most important is methyl-n-amyl ketone, to which the oil owes its fresh and fruity aroma. Other substances present in traces are methyl salicylate, methyl benzoate, methyl alcohol, benzyl alcohol, furfuryl alcohol, furfural, methyl furfural, dimethyl furfural, pinene, methyl-n-heptyl ketone, methyl-n-amyl carbinol (2-heptanol), methyl-n-heptyl carbinol and vanillin.
 
 The oil, obtained by solvent extraction of cloves, contains little or no caryophyllene, but contains epoxydihydrocaryophyllene. The oil contains eugenone, eugenine, eugenitine and iso-eugenitol These substances are practically odourless. The oil also contains sesquiterpenes, a-cubebene, a-copaene, g- and d-cadinene, caryophyllene, caryophyllene oxide, a-humulene, a-humulene epoxide besides eugenol. The leaves yield an essential oil (3%) on steam distillation. It contains a-cubebene, a-copaene, b-caryophyllene, a-humulene, eugenol, isoeugenol acetate, eugenol acetate and farnesol. A neutral sesqueterpene fraction of an Indonesian sample contained a-cubenene, a-ylangene, a-copaene, bourbonene, caryophyllene, a-humulene, allo-aromadendrene, a-muurolene, zinziberine, d-cadinene, calamenene, a-calacorene, caryophyllene oxide, ledol, palustrol, d-cadinol, cubenol, calamenenol, cadalene, a-cadinol and humuladienone. Presence of ethyl acetate, ethanol, limonene, pinenes, p-cymene, 1,8-cineole, 4-methyl-3-pentenyl-3-furan, linalool, carvone, linalyl acetate, etc. are also reported in the clove leaf oil. The leaves also contain 3,4-dihydroxy phenethyl alcohol and 3,4-dihydroxy benzoic acid having anti-inflammatory action.

Pharmacology

The compounds of clove show significant activity as inducers of detoxifying enzyme-glutathione S-transferase in mouse liver and intestines. This ability is correlated with their activity in inhibiting the chemical carcinogenesis, and as anticancer agents. The methanolic extract of clove exhibits anti-tumour activity. The methanolic extract showed remarkable induction of differentiation of myeloid leukaemia (MI) cells into macrophage like cells. Oleanolic acid and crategolic acid are the active principles of the extract.

Toxicology

There is no adverse is reported on use of this herb as drug.

Uses:
The oil is used in sustained release topical analgesic preparations and used in dentifrices for removal of stain in teeth, in root canal filling material, as salivary stimulator in sublingual pharmaceutical compositions. Also in buccal deodarant tapes and in dental bandages for protection to gingival tissue. The oil is used in topical formulations for use in cryotherapy for treating circulatory diseases such as posttraumatic oedema. The Eugenol and acetyl eugenol components of the oil inhibit arachidonate-adrenaline and collagen induced platelet aggregation. The oil should be used in restricted concentration because of photo-toxic and photo-irritant activity. Clove oil is also an ingredient of hair and body shampoos. It has Insulin potentiating activity. The oil exhibits anti-implantation activity.The cloves are highly esteemed as a flavouring material and are extensively used, whole or in ground form, as a culinary spice. They impart a warming quality to food, and are used for flavouring ham, roasts, pickles, preserves, ketchups and sauces, as seasoning for sausages, dressing for poultry and meat, and in specialized spices for mincemeat and pastry. Because of their pungent and aromatic taste, cloves are favoured for making cakes, pies, puddings, cookies and candy. They are used in making spiced wines and for scenting the chewing-tobacco; they form an ingredient of betel-chew. In Indonesia, cloves are used in making a special brand of cigarettes- Keretek, which crackle while burning.