Although lemon thyme (T. citriodorus) is sometimes used as a culinary herb, it is the common thyme that first crept into use in Roman kitchens, accompanying cheeses and used in alcoholic beverages. The Romans took the herb with them throughout Europe, and it was naturalized in England by at least the 16th century. It may have first been introduced to England by monastic orders as early as the 13th century. In 1661, the diarist and gardener John Evelyn published the very first book on air pollution, titled the Fumifugium (or The Inconveniencie of the Aer and Smoak of London Dissipated), in which he recommended that thyme be strewn about to “improve and meliorate the Aer about London.”
In the 1720s, the German pharmacist Kaspar Neumann isolated the essential oil thymol, which gives thyme its flavour, aroma, and medicinal qualities. Thymol is a crystalline substance that can be used as a preservative, an anesthetic, or for many other purposes. Book restorers sometimes place thymol in sealed bags with books in order to kill mould spores. It has been used to treat hookworm and ringworm, and as an antiseptic ingredient in mouthwash. Prior to the early 20th century, most of the world’s supply of thymol came from ajowan seeds – and the chemical can also be extracted from bergamot (Monarda sp.). Lovers of Earl Grey tea will know its flavour well.
Creeping thyme (T. serphyllum) is a popular decorative groundcover, and a famous source of nectar for honeybees, but is not used in the kitchen. Common thyme, on the other hand, has masses of uses, and retains its flavour as a dried herb longer than most. It is widely used in the cuisines of the Mediterranean, from North African to Levantine to French. Thyme is a key ingredient of the French herb blends bouquet garni and herbes de Provence. It is also widely used in Caribbean cooking, and an important ingredient in Jamaican jerk sauce. Like bay leaves, thyme needs to be added to dishes early, as it releases its flavours gradually, even when fresh.