Thyme (Thymus) (pronounced "time") is a genus of perennial plants. There are about 350 different species of thyme. They are herbaceous plants and sub-shrubs. They can grow to about 40 cm tall. They are the family Lamiaceae and native to Europe, North Africa and Asia.

The stems are usually narrow, sometimes even wiry. The leaves are evergreen in most species. They are arranged in opposite pairs, oval, entire, and small, 4–20 mm long. The flowers are in dense terminal heads, with an uneven calyx, with the upper lip three-lobed, and the lower cleft; the corolla is tubular, 4–10 mm long, and white, pink or purple.

Thymus species are used as food plants by the larvae of some Lepidoptera species including Chionodes distinctella and Coleophora species.

History 
Ancient Egyptians used thyme for embalming. The ancient Greeks used it in their baths and burnt it as incense in their temples. They believed that thyme was a source of courage. It was thought that the spread of thyme throughout Europe was thanks to the Romans, as they used it to purify their rooms. In the European Middle Ages, the herb was placed under pillows. This was done to help sleep and ward off nightmares. (Huxley 1992). In this period, women would also often give knights and warriors gifts that included thyme leaves. People believed it would bring courage to the bearer. Thyme was also used as incense and placed on coffins during funerals as it was supposed to assure passage into the next life.

Cultivation 
Thyme is widely grown as a herb. Usually it is grown for its strong flavour, which is due to its content of thymol.

Thyme likes a hot sunny location with good-draining soil. It is planted in the spring and later grows as a perennial. It can be propagated by seed, cuttings, or by dividing rooted sections of the plant. It tolerates drought well.

Thyme keeps its flavour on drying better than many other herbs.

Culinary use 
Thyme is widely used for cooking. Thyme is a basic ingredient in French and Italian cuisines, and in those derived from them. It is also widely used in Caribbean cuisine.

Thyme is often used to flavour meats, soups and stews. It has a particular affinity to and is often used as a primary flavour with lamb, tomatoes and eggs.

Thyme, while flavourful, does not overpower and blends well with other herbs and spices. In French cuisine, along with bay and parsley it is a common component of the bouquet garni, and of herbes de Provence. In some Middle Eastern countries, the condiment za'atar contains thyme as a vital ingredient.

Thyme is sold both fresh and dried. The fresh form is more flavourful but also less convenient; storage life is rarely more than a week. While summer-seasonal, fresh thyme is often available year-round. Fresh thyme is commonly sold in bunches of sprigs. A sprig is a single stem snipped from the plant. It is composed of a woody stem with paired leaf or flower clusters ("leaves") spaced ½ to 1" apart. A recipe may measure thyme by the bunch (or fraction thereof), or by the sprig, or by the tablespoon or teaspoon. If the recipe does not specify fresh or dried, assume that it means fresh.

Thyme retains its flavour on drying better than many other herbs. Dried, and especially powdered thyme occupies less space than fresh, so less of it is required when substituted in a recipe. As with bay, thyme is slow to release its flavours so it is usually added early in the cooking process.

Medicinal use 
The essential oil of common thyme (Thymus vulgaris) is made up of 20-55% thymol. Thymol, an antiseptic, is the main active ingredient in Listerine mouthwash. Before the advent of modern antibiotics, it was used to medicate bandages. It has also been shown to be effective against the fungus that commonly infects toenails.

A tea made by infusing the herb in water can be used for cough and bronchitis. Medicinally thyme is used for respiratory infections.  Because it is antiseptic, thyme boiled in water and cooled is very effective against inflammation of the throat. The inflammation will normally disappear in 2 – 5 days. Other infections and wounds can be dripped with thyme.

In traditional Jamaican childbirth practice, thyme tea is given to the mother after delivery of the baby. Its oxytocin-like effect causes uterine contractions and more rapid delivery of the placenta but this was said by Sheila Kitzinger to cause an increased prevalence of retained placenta.

Important species 
Thymus vulgaris (common thyme or garden thyme) is a commonly used culinary herb. It also has medicinal uses. Common thyme is a Mediterranean perennial which is best suited to well-drained soils and enjoys full sun.

Thymus herba-barona (caraway thyme) is used both as a culinary herb and a groundcover, and has a strong caraway scent due to the chemical carvone.

Thymus × citriodorus (citrus thyme; hybrid T. pulegioides × T. vulgaris) is also a popular culinary herb, with cultivars selected with flavours of various Citrus fruit (lemon thyme, etc.)

Thymus pseudolanuginosus (woolly thyme) is not a culinary herb, but is grown as a ground cover.

Thymus serpyllum (wild thyme) is an important nectar source plant for honeybees. All thyme species are nectar sources, but wild thyme covers large areas of droughty, rocky soils in southern Europe (Greece is especially famous for wild thyme honey) and North Africa, as well as in similar landscapes in the Berkshire Mountains and Catskill Mountains of the northeastern US.

Cultivars 
There are a number of different cultivars of thyme with established or growing popularity, including:
 Lemon thyme—actually smells lemony
 Variegated lemon thyme—with bi-color leaves
 Orange thyme—an unusually low-growing, ground cover thyme that smells like orange
 Creeping thyme—the lowest-growing of the widely used thymes, good for walkways
 Silver thyme—white/cream variegated
 English thyme—the most common
 Summer thyme—unusually strong flavor

References

Other sources 
 Flora of China: Thymus
 Flora Europaea: Thymus
 Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan.
 Rohde, E. S. (1920). A Garden of Herbs.

Other websites 
 Plants for a Future, database entry
 'A Modern Herbal' (Grieves 1931)

Lamiaceae
Herbs