Melaleuca
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 M. armillaris foliage and flowers
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236; see List of Melaleuca species |
Melaleuca is a genus of plants in the myrtle family Myrtaceae. It currently contains 236 species, all of which occur in Australia. About 230 species are endemic to Australia, the few remaining species occurring as far afield as Indonesia, New Guinea, New Caledonia and even Malaysia.
The species are shrubs and trees growing (depending on species) to 2–30 m tall, often with flaky, exfoliating bark. The leaves are evergreen, alternately arranged, ovate to lanceolate, 1-25 cm long and 0.5-7 cm broad, with an entire margin, dark green to grey-green in colour. The flowers are produced in dense clusters along the stems, each flower with fine small petals and a tight bundle of stamens; flower colour varies from white to pink, red, pale yellow or greenish. The fruit is a small capsule containing numerous minute seeds.
Melaleuca is closely related to Callistemon, the main difference between the genera is that the stamens are generally free in Callistemon but grouped into bundles in Melaleuca.
In the wild, Melaleuca plants are generally found in open forest, woodland or shrubland, particularly along watercourses and the edges of swamps.
The best-accepted common name for Melaleuca is simply melaleuca; however most of the larger species are also known as paperbarks, and the smaller types as honey myrtles. Some melaleucas are used in the manufacture of an essential oil called tea tree oil and called "tea trees", which is confusing, as "tea tree" has also been used for several other plants, including Leptospermum, a related and superficially similar-looking genus. In particular, the paperbark tree Melaleuca alternifolia was dubbed the "tea tree" as its foliage when steeped in water produces a brown tincture faintly resembling tea to the early Europeans, although it was generally recognised to be only a very poor (and potentially toxic) substitute. Similarly small bodies of water near Melaleuca scrub are sometimes coloured brown due to the seepage from the leaves.
In Australia, Melaleuca species are sometimes used as food plants by the larvae of hepialid moths of the genus Aenetus including A. ligniveren. These burrow horizontally into the trunk then vertically down.
Melaleucas are popular garden plants, both in Australia and other tropical areas worldwide. In Hawaii and the Florida everglades, Melaleuca quinquenervia (Broad-leaved Paperbark) was introduced in order to help drain low-lying swampy areas. It has since gone on to become a serious invasive weed. Melaleuca populations have nearly quadrupled in southern Florida over the past decade, as can be noted on IFAS's SRFer Mapserver
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[edit] Uses
[edit] Traditional Aboriginal uses
Aborigines used the leaves traditionally for many medicinal purposes, including chewing the young leaves to alleviate headache and for other ailments.
The softness and flexibility of the paperbark itself made it an extremely useful tree to Aboriginal people. It was used to line coolamons when used as cradles, as a bandage, as a sleeping mat, and as material for building humpies. It was also used for wrapping food for cooking (in the same way aluminium foil is today), as a disposable raincoat, and for tamping holes in canoes. In the Gadigal language, it is called Bujor. [1]
[edit] Modern uses
Scientific studies have shown that tea tree oil made from Melaleuca alternifolia is a highly effective topical antibacterial and antifungal, although it may be toxic when ingested internally in large doses or by children. In rare cases, topical products can be absorbed by the skin and result in toxicity.
The oils of Melaleuca can be found in organic solutions of medication that claims to eliminate warts, including the Human papillomavirus. No scientific evidence proves this claim (reference: "Forces of Nature: Warts No More").
Melaleuca oils are the active ingredient in Burn-Aid, a popular minor burn first aid treatment (an offshoot of the brandname Band-Aid).
Melaleuca oils (tea tree oil) is also used in many pet fish remedies (such as Melafix and Bettafix) to treat bacterial and fungal infections. Bettafix is a lighter dilution of tea tree oil while Melafix is a stronger dilution. It is most commonly used to promote fin and tissue regrowth. The remedies are often associated with Betta fish (Siamese Fighting Fish) but are also used with other fish.
[edit] Weeds
Melaleucas were introduced to Florida in the United States in the early 20th century to assist in drying out swampy land and as garden plants. They have become very effective at drying wetlands and are now considered to be an ecological weed, especially in the Florida Everglades.[2]
 A Melbourne paperbark |
 A paperbark in Melbourne |
 Melaleuca quinquenervia bark showing the papery exfoliation from which the common name 'paperbark' derives |
 Paperbark trees in Tasmania after sunset |
 19th century illustration of Melaleuca leucadendra |
[edit] References
- ^ http://www.rbgsyd.nsw.gov.au/information_about_plants/botanical_info/aboriginal_bush_foods
- ^ Melaleuca. Plant Conservation Alliance's Alien Plant Working Group Least Wanted. National Park Service (United States) (27 June 2006). Retrieved on January 13, 2007.
- Takarada K et al. (2004). A comparison of the antibacterial efficacies of essential oils against oral pathogens. Oral Microbiol. Immunol. 19 (1): 61-64.
- Hammer KA et al. (2003). Susceptibility of oral bacteria to Melaleuca alternifolia (tea tree) oil in vitro. Oral Microbiol. Immunol. 18 (6): 389-392.
- Hammer KA et al. (2003). Antifungal activity of the components of Melaleuca alternifolia (tea tree) oil. J. Appl. Microbiol. 95 (4): 853-860.
- Oliva B et al. (2003). Antimycotic activity of Melaleuca alternifolia essential oil and its major components. Lett. Appl. Microbiol. 37 (2): 185-187.
- Mondello F et al. (2003). In vitro and in vivo activity of tea tree oil against azole-susceptible and -resistant human pathogenic yeasts. J. Antimicrob. Chemother. 51 (5): 1223-1229.
[edit] See also
[edit] External links
