Melaleuca is a genus of plants in the myrtle family Myrtaceae. There are well over 200 recognised species, most of which are endemic to Australia. 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 being 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. They are also sometimes referred to as punk trees.

One well-known melaleuca, the Ti tree (aka tea tree), Melaleuca alternifolia, is notable for its essential oil which is both anti-fungal, and antibiotic, while safely usable for topical applications. This is produced on a commercial scale, and marketed as Tea Tree Oil. The Ti tree is not actually usable for making tea, but presumably named for the brown colouration of many water courses caused by shed leaves from this species and other similar species trees, for a famous example see Brown Lake (Stradbroke Island)). The name "tea tree" is also used for a related genus, Leptospermum. Both Leptospermum and Melaleuca are myrtles of the family, Myrtaceae.

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 with potentially very serious consequences being that the plants are highly flammable and spread agreesively. Melaleuca populations have nearly quadrupled in southern Florida over the past decade, as can be noted on IFAS's SRFer Mapserver

The genus Callistemon was recently placed into Melaleuca.

Uses

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.

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.

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. Once widely planted in Florida, it forms dense thickets and displaces native vegetation on of wet pine flatwoods, sawgrass marshes, and cypress swamps in the southern part of the state. [It is prohibited by DEP and listed as a noxious weed by FDACS.

References

See also

• List of Melaleuca species
• Poliopaschia lithochlora, a proposed agent for eradication

External links

• TAME Melaleuca Project - Institute of Food and Agricultural Sciences
• Association of Societies for Growing Australian Plants - Melaleuca Page