Eucalyptus

A large and important genus of Australian forest trees; includes about 500 species in the family Myrtaceae. Only two species occur naturally outside Australia in the adjacent islands. Eucalypts occur throughout Australia except in coastal tropical and subtropical rainforests in Queensland and New South Wales and in temperate rainforests in Victoria and Tasmania. They are confined to water courses in the extensive arid zones of central and northwest Australia. Eucalypts grow from sea level to tree line (6600 ft or 2000 m). Because of its large geographic range the genus exhibits many habits, from tall trees to multistemmed, shrubby species called mallees.
Eucalyptus is an evergreen genus with four different leaf types—seedling, juvenile, intermediate, and adult—depending on plant maturity. Juvenile leaves of some species, particularly those that are silvery blue and oval, are extensively used for floral decorations. Most species have white or cream flowers. Some species, particularly those from Western Australia, are planted widely as ornamentals.
Eucalypts have been planted widely for commercial use in Brazil and other South American countries, Africa, the Indian subcontinent, and the Middle East. They are used extensively for fuel and construction and are an important component of third world economies. Foliage of some species yields essential oils for medicines and perfumes. Tannins are extracted from the bark of certain species.

Description

The eucalyptus tree is a large, fast-growing evergreen that is native to Australia and Tasmania. The tree can grow to 375-480 feet (125-160 meters). Eucalyptus belongs to the myrtle family. There are more than 300 species of eucalyptus, and Eucalyptus globulus is the most well-known species. One species (E. amygdalin) is the tallest tree known in the world. The tree grows best in areas with an average temperature of 60°F (15°C).
The name is actually derived from the Greek word “eucalyptos,” which means “well covered,” and refers to the cuplike membrane that covers the budding flowers of the tree.
The bluish green leaves carry the medicinal properties of the tree and grow to a length of 6-12 inches (15-30 cm). While the leathery leaves are the sole food for koala bears, the leaves also contain a fragrant volatile oil that has antiseptic, expectorant, antibacterial, anti-inflammatory, deodorant, diuretic, and antispasmodic properties. Other constituents of the leaves include tannins, phenolic acids, flavonoids (eucalyptin, hyperin, hyperoside, quercitin, quercitrin, rutin), sesquiterpenes, aldehydes, and ketones.
Eucalyptus oil is obtained through a steam distillation process that removes the oil from the fresh, mature leaves and branch tips of older trees. Approximately 25 species of eucalyptus trees in Australia are grown for their oil.
There are three grades of eucalyptus oil: medicinal, which contains the compound eucalyptol (also called cineol); industrial, in which a component of the oil is used in mining operations; and aromatic, which is used in perfumes and fragrant soap products. These oils vary greatly in character. When choosing an oil for therapeutic use, it is important to know from what species the oil was derived. Species used medicinally include E. globulus, which contains up to 70% eucalyptol; E. polybractea, which contains 85% eucalyptol; and E. Smithii. Eucalpytus amygdalina and E. dives contain little eucalyptol and are used to separate metallic sulfides from ores in the mining industry. Eucalyptus citriodora contains a lemon-scented oil and is an ingredient in perfumes, as is E. odorata and E. Sturtiana. Two species, E. dives and E. radiata, have oils with a strong peppermint odor.
The most common species grown for its medicinal oil is Eucalyptus globulus. The eucalyptol found in this species is a chief ingredient in many over-the-counter cold and cough remedies, such as cough lozenges, chest rubs, and decongestants. It acts to stimulate blood flow and protects against infection and germs. The British Pharmocopoeia requires that commercial eucalyptus oils contain 55% eucalyptol by volume.

General Use

Eucalyptus is most popular for its ability to clear congestion due to colds, coughs, flu, asthma, and sinusitis. The tannins found in eucalyptus have astringent properties that reduce mucous membrane inflammation of the upper respiratory tract. Eucalyptol, the chemical component of the oil, works to loosen phlegm. Cough drops containing eucalyptus promote saliva production, which increases swallowing and lessens the coughing impulse. Earaches can also be treated with eucalyptus. When inhaled, the eucalyptus fumes open the eustachian tubes, draining fluids and relieving pressure. Eucalyptus enhances breathing, which makes it an effective remedy for asthma, bronchitis, sinusitis, whooping cough, and colds.
Eucalyptus is a component of many topical arthritis creams and analgesic ointments. When applied to the skin, eucalyptus stimulates blood flow and creates a warm feeling to the area, relieving pain in muscles and joints.
The oil extracted from the eucalyptus leaf has powerful antiseptic, deodorizing, and antibacterial properties. It is especially effective in killing several strains of Staphylococcus bacteria. A mixture of 2% eucalyptus oil evaporated in an aroma lamp has been shown to destroy 70% of the Staphylococcus bacteria in the affected room. When the oil is applied to cuts, scrapes, and other minor wounds, it inhibits infections and viruses. A 2002 report out of Australia made researchers around the world take note when two cases of patients with staph infections resistant to traditional antibiotic therapy responded to a mixture of eucalyptus leaf oil abstract. The Australian researchers recommended formal clinical trials to test the therapy, based on an ancient aboriginal remedy. Eucalyptus also fights plaque-forming bacteria and is used to treat gum disease and gingivitis.
In large doses, the oil can be a kidney irritant and can induce excretion of bodily fluids and waste products. Eucalyptus oil added to water may be gargled to relieve sore throat pain or used as a mouthwash to heal mouth sores or gum disorders. Consequently, eucalyptus is an ingredient in many commercial mouthwashes.
Eucalyptus’ pain-relieving properties make it a good remedy for muscle tension. One study showed that a mixture of eucalyptus, peppermint, and ethanol oils successfully relieved headache-related muscle tension.
Eucalyptus may lower blood sugar levels. Placing a drop of the oil on the tongue may reduce nausea. The oil has also been used to kill dust mites and fleas.
Eucalyptus oil is one of the most well-known fragrances in aromatherapy. Two species of eucalyptus are used in aromatherapy oils: E. globulus and E. citriodora. The essential oil of eucalyptus is used to relieve cramps, cleanse the blood, heal wounds, disinfect the air, and to treat conditions such as asthma, bronchitis, throat and sinus infections, fevers, kidney infections, rheumatism, bladder infections, and sore muscles.
The essential oil can be diluted and added to a massage oil to ease aching muscles. The oil can be added to hot water and inhaled to reduce nasal congestion. It can also be diffused in the room of a sick patient to disinfect the air.
Some believe that inhaling the diffused oil can enhance concentration and thought processes. Studies have shown that inhalation of the cineole compound of eucalyptus stimulates coordination and motor activities in mice. Eucalyptus oil may also uplift the spirit during times of emotional overload or general sluggishness.
Applying a diluted oil to the skin instead of inhaling it increases the rate of absorption into the blood. Often the speed with which it is absorbed is so fast, the odor can be detected on the breath within minutes.
The oil is also an effective febrifuge, and a cold compress with eucalyptus oil added to it has a cooling effect that is useful in helping to reduce a fever. The essential oil of eucalyptus is also used to treat wounds, herpes simplex virus, skin ulcers, and acne. Combined with water, the oil makes an effective insect repellant. Because of its skin-moistening properties, the oil is often an ingredient in dandruff shampoo.

Plantation and ecological problems

Eucalypts were first introduced to the rest of the world by Sir Joseph Banks, botanist, on the Cook expedition in 1770. They have subsequently been introduced to many parts of the world, notably California, Brazil, Ecuador, Ethiopia, Morocco, Portugal, South Africa, Israel, Galicia and Chile. Several species have become invasive and are causing major problems for local ecosystems. In Spain, they have been planted in pulpwood plantations, replacing native oak woodland. As in other such areas, while the original woodland supports numerous species of native animal life (insects, birds, salamanders, etc.), the eucalypt groves are inhospitable to the local wildlife which is not adapted to them, leading to silent forests and the decline of wildlife populations. On the other hand, eucalyptus are the basis for several industries, such as sawmilling, pulp, charcoal and others.

Sources: Answers, Wikipedia

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