Lavandula (common name lavender)
Commercially, the plant is grown mainly for the production of essential oil of lavender. This has antiseptic and anti-inflammatory properties, and can be used as a natural mosquito repellent. These extracts are also used as fragrances for bath products.
English lavender (Lavandula angustifolia) yields an essential oil with sweet overtones, and can be used in balms, salves, perfumes, cosmetics, and topical applications. Lavandin, Lavandula × intermedia (also known as Dutch lavender), yields a similar essential oil, but with higher levels of terpenes including camphor, which add a sharper overtone to the fragrance.
The lavandins Lavandula × intermedia are a class of hybrids of L. angustifolia and L. latifolia. The lavandins are widely cultivated for commercial use, since their flowers tend to be bigger than those of English lavender and the plants tend to be easier to harvest, but lavandin oil is regarded by some to be of a lower quality than that of English lavender, with a perfume less sweet.
Spearmint, or spear mint (binomial Mentha spicata, synonym Mentha viridis),
Spearmint is used for its aromatic oil, referred to as oil of spearmint. The most abundant compound in spearmint oil is R-(–)-carvone, which gives spearmint its distinctive smell. Spearmint oil also contains significant amounts of limonene, dihydrocarvone, and 1,8-cineol. Unlike oil of peppermint, oil of spearmint contains minimal amounts of menthol and menthone. It is used as a flavoring for toothpaste and confectionery, and is sometimes added to shampoos and soaps.
Used as a fumigant, spearmint essential oil is an effective insecticide against adult moths.
Eucalyptus oil is readily steam distilled from the leaves and can be used for cleaning and as an industrial solvent, as an antiseptic, for deodorizing, and in very small quantities in food supplements, especially sweets, cough drops, toothpaste and decongestants. It has insect repellent properties (Jahn 1991 a, b; 1992), and is an active ingredient in some commercial mosquito repellents (Fradin & Day 2002). Eucalyptus globulus is the principal source of eucalyptus oil worldwide.
Melaleuca alternifolia is notable for its essential oil which is both antifungal and antibiotic, while safely usable for topical applications. This is produced on a commercial scale and marketed as tea tree oil.
Melaleuca cajuputi is used to produce a similar oil, known as cajuput oil, which is used in Southeast Asia to treat a variety of infections and to add fragrance to food and soaps.
Syzygium aromaticum (Clove)
The U.S. Food and Drug Administration (FDA) has reclassified eugenol (one of the chemicals contained in clove oil), downgrading its effectiveness rating. The FDA now believes not enough evidence indicates clove oil or eugenol is effective for toothache pain or a variety of other types of pain.
Studies to determine its effectiveness for fever reduction, as a mosquito repellent, and to prevent premature ejaculation have been inconclusive. It remains unproven whether clove may reduce blood sugar levels.
In addition, clove oil is used in preparation of some toothpastes and Clovacaine solution, which is a local anesthetic used in oral ulceration and inflammation. Eugenol (or clove oil generally) is mixed with zinc oxide to form a temporary tooth cavity filling.
Clove oil can be used to anesthetize fish, and prolonged exposure to higher doses (the recommended dose is 400 mg/l) is considered a humane means of euthanasia.
Ajwain is used as medicinal plant in traditional Ayurvedic medicine; primarily for stomach disorders such as indigestion, flatulence, and others but also for its supposed antispasmodic and carminative properties. In general the crushed fruits are applied externally as a poultice.