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Melaleuca

From Wikipedia, the free encyclopedia
For other uses, seeMelaleuca (disambiguation).
"Paperbark" redirects here. For other uses, seePaperbark (disambiguation).

Melaleuca
Melaleuca armillarisfoliage and flowers
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Myrtales
Family: Myrtaceae
Subfamily: Myrtoideae
Tribe: Melaleuceae
Genus: Melaleuca
L.[1]
Species

SeeList ofMelaleucaspecies

Synonyms[1]
Genus synonymy

Melaleuca(/ˌmɛləˈljuːkə/) is agenusof nearly 300speciesofplantsin the myrtlefamily,Myrtaceae,commonly known aspaperbarks,honey-myrtles,bottlebrushesortea-trees(although the last name is also applied to species ofLeptospermum).[2]: 19 They range in size from small shrubs that rarely grow to more than 16 m (52 ft) high, to trees up to 35 m (115 ft). Their flowers generally occur in groups, forming a "head" or "spike" resembling abrushused for cleaning bottles, containing up to 80 individual flowers.

Melaleucas are an important food source fornectarivorousinsects, birds, and mammals. Many are popular garden plants, either for their attractive flowers or as dense screens and a few have economic value for producing fencing and oils such as"tea tree" oil.Most melaleucas areendemictoAustralia,with a few also occurring inMalesia.Seven are endemic toNew Caledonia,and one is found only on Australia'sLord Howe Island.Melaleucas are found in a wide variety of habitats. Many are adapted for life in swamps and boggy places, while others thrive in the poorest of sandy soils or on the edge of saltpans. Some have a wide distribution and are common, whilst others are rare and endangered. Land clearing, exoticmyrtle rust,and especially draining and clearing of swamps threaten many species.

Description[edit]

Melaleucas range in size from small shrubs such asM. aspalathoidesandM. concinnawhich rarely grow to more than 1 m (3 ft 3 in) high, to trees likeM. cajuputiandM. quinquenervia,which can reach 35 m (115 ft). (One specimen ofM. cajuputireached a height of 46 m (151 ft).)[3]

Many, likeM. lineariifolia,are known as paperbarks and have bark that can be peeled in thin sheets, whilst about 20% of the genus, includingM. bracteata,have hard, rough bark and another 20% have fibrous bark. Every species in the genus is anevergreen,and the leaves vary in size from minute and scale-like (M. micromera) to 270 mm (11 in) long (M. leucadendra). Most have distinct oil glands dotted in the leaves, making the leaves aromatic, especially when crushed.[2]: 20–21 

Melaleuca flowers are usually arranged in spikes or heads. Within the head or spike, the flowers are often in groups of two or three, each flower or group having a paperybractat its base. Fivesepalsoccur, although these are sometimes fused into a ring of tissue and fivepetalswhich are usually small, not showy, and fall off as the flower opens or soon after. Thestamensvary greatly in colour, from white to cream or yellow, red, or mauve with their yellow tips (theanthers) contrasting with their "stalks" (filaments).[2]: 20–21 

The fruit are woody, cup-shaped, barrel-shaped, or almost sphericalcapsules,often arranged in clusters along the stems. The seeds are sometimes retained in the fruit for many years, only opening when the plant, or part of it, dies or is heated in abushfire.In tropical areas, seeds are released annually in thewet season.[2]: 25–26 

Etymology[edit]

The nameMelaleucais derived from theAncient Greekμέλας (mélas) meaning "dark" or "black" and λευκός (leukós) meaning "white",[4][5]apparently because one of the first specimens described had fire-blackened white bark.[6]The common name "tea tree" has been applied to species in the generaLeptospermum,Melaleuca,Kunzea,andBaeckeabecause the sailors on theEndeavourused the leaves of a shrub from one of these groups as a replacement for tea (Camellia sinensis)during CaptainJames Cook's 1770 voyage to Australia.[7]

Taxonomy[edit]

M. quinquenerviabark showing the papery exfoliation from which the common name "paperbark" derives

The first known description of aMelaleucaspecies was written byRumphiusin 1741, inHerbarium amboinense[8]before the present system of naming plants was written. The plant he calledArbor albais now known asMelaleuca leucadendra.The nameMelaleucawas first used byLinnaeusin 1767.[9]Many species previously known asMetrosideroswere then placed inMelaleuca.In Australia,Melaleucais the third most diverse plant genus with up to 300 species.[10]

The genusCallistemonwas raised byRobert Brown,who noted its similarity toMelaleuca,distinguishing it only on the basis of whether the stamens are free of each other, or joined in bundles.[11]Botanists in the past, includingFerdinand von MuellerandLyndley Craven[12]have proposed uniting the two genera but the matter is not decided. Evidence from DNA studies suggests that eitherCallistemonand some other genera be incorporated intoMelaleucaor that at least 10 new genera be created from the present genus.[2]: 16–17 [13][14]

In 2014,Lyndley Cravenand others proposed, on the basis of DNA evidence and a lack of morphological support,[14]that species in the generaBeaufortia,Calothamnus,Conothamnus,Eremaea,Lamarchea,Petraeomyrtus,PhymatocarpusandRegeliabe transferred toMelaleuca.[15]TheWorld Checklist of Selected Plant Familiesmaintained by theRoyal Botanic Gardens, KewlistsCalothamnusand the other genera as synonyms of the accepted genusMelaleuca.[16]The move has not been adopted by all Australianherbariawith some taxonomists, includingAlex Georgeopposing the move.[17]

Distribution and habitat[edit]

Paperbark trees on theEast Alligator Riverin theNorthern Territory

Most melaleucas occur naturally only on the Australian mainland. Eight occur inTasmania,but only two are endemic to that island. One (M. howeana) is endemic toLord Howe Islandand seven are endemic toGrande Terre,the main island of New Caledonia.[18]A few tropical species also occur inPapua New Guinea,and the distribution of one subspecies,Melaleuca cajuputisubsp.cumingianaextends as far north asMyanmar,Thailand,andVietnam.The southwest ofWestern Australiahas the greatest density of species, and in the tropical north of the continent, species such asM. argenteaandM. leucadendraare the dominant species over large areas.

Melaleucas grow in a range of soil types and many tolerate occasional or even permanent waterlogging. Some species, especially the South Australian swamp paperbark,M. halmaturorum,thrive in saline soils where few other species survive. Many are fire tolerant, regenerating fromepicormic budsor bycoppicing,but no melaleucas occur in rainforest and few species occur in the arid zone.[2]: 26–31 

Ecology[edit]

Melaleucas are mostly pollinated by insects, including the introduced honey bee (Apis mellifera), flies, beetles, wasps andthrips.Birds such aslorikeetsandhoneyeatersas well asbatsoften visit the flowers and are probably also pollinators.[2]: 23 [19]

Some species ofMelaleuca,especiallyM. alternifolia,are cultivated for the production of tea tree oil, and in plantations are susceptible to a number of insect pests. The most significant of these is thechrysomelidParopsisterna tigrina,but otherbeetles,cutwormcaterpillars (Agrotis species),psyllids,mole crickets (Gryllotalpa), and others cause significant damage. More than 100 species of insects are known to feed on melaleucas. Native stands have fewer predators, but tea treesawfly(Pterygophorusspecies) andlongicorn beetlesare often found.[20]The scale insectBeesonia ferrugineusforms round, fluffy-looking galls on branches of severalMelaleucaspecies.[21]

Melaleucas are also susceptible to myrtle rust (Puccinia psidii) which can result in damage to soft plant material and the death of highly susceptible hosts. Myrtle rust is common in eastern Australia, includingTasmaniaand has been detected in theTiwi Islands.[22]

Invasive species[edit]

Main article:Melaleuca quinquenervia § Status in the United States

Melaleuca quinquenervia(broad-leaved paperbark) is the most damaging of 60 exotic species introduced to theFloridaEvergladesto help drain low-lying swampy areas. Introduced in the early 20th century, it has become a seriousinvasive species,with damaging effects including the displacement of native species, reduction in wildlife habitat, alteration of hydrology, modification of soil, and changes in fire regimes.[23][24][25]

Uses[edit]

Traditional Aboriginal uses[edit]

Aboriginal Australiansused several species ofMelaleucato make rafts, as roofing for shelter, bandages, and food preparation.[26]"Bee bread" and honey were collected from the hives of nativestingless beesin melaleuca forests in theNorthern Territory.[27]TheBundjalung peopletraditionally lived in the area of north-easternNew South WaleswhereMelaleuca alternifoliaisendemic,and they treated skin infections by crushing the leaves of that species over skin infections then covering the area with a warm mudpack.[28]

Essential oils[edit]

Melaleuca alternifoliais notable for itsessential oil,which hasantifungalandantibioticproperties in vitro.[29][30]Though it is safe fortopicalapplications,[31]tea tree oil is toxic if ingested orally.[29]

The oil is produced on a commercial scale and marketed astea tree oil.[32]Melaleuca cajuputiis used to produce a similar oil, known ascajuput oil,which is used inSoutheast Asiato treat a variety of infections and to add fragrance to food and soaps.[33]

Horticulture[edit]

Melaleucas are popular garden plants, both in Australia and other tropical areas worldwide. The first to be cultivated were grown in England from seed in 1771. Some melaleucas are commonly cultivated, grown as trees for parks and large gardens (such asMelaleuca leucadendra)[34]or as ornamentals (sometimes asCallistemon) such asM. citrina(Callistemon citrinus),M. hypericifoliaandM. wilsonii.[35]

Melaleucas used in horticulture[edit]

In popular culture[edit]

Tea trees (spelledTi-Trees) are specifically mentioned in the lyrics of a short aria 'Joy' published around 1916 by J.D.Fletcher & Co of London, by Australian composerArthur Chanter(1866-1950).[36]

See also[edit]

References[edit]

  1. ^ab"Melaleuca".Plants of the World Online/Kew Science.Retrieved23 July2020.
  2. ^abcdefgBrophy, Joseph J.; Craven, Lyndley A.; Doran, John C. (2013).Melaleucas: their botany, essential oils and uses.Canberra: Australian Centre for International Agricultural Research.ISBN9781922137517.
  3. ^Boland, Douglas J. (2006).Forest trees of Australia(5 ed.). Collingwood, Vic.: CSIRO. p. 612.ISBN9780643069695.
  4. ^Gledhill, David (2006).The names of plants(4th ed.). Cambridge: Cambridge University Press. p. 254.ISBN978-0-521-86645-3.
  5. ^Moore, Bruce, ed. (2002).The Australian Oxford Dictionary(1999 ed.). South Melbourne, Vic: Oxford University Press. p. 842.ISBN0195507932.
  6. ^Holliday, Ivan (2004).Melaleucas: a field and garden guide(2nd ed.). Frenchs Forest, N.S.W.: Reed New Holland Publishers. pp. 6–9.ISBN1876334983.
  7. ^Southwell, Ian (1999). Southwell, Ian; Lowe, Robert (eds.).Tea tree: The genus Melaleuca.Amsterdam: Harwood Academic. pp. 1–2.ISBN9057024179.
  8. ^Rumphius, Georg (1741).Herbarium amboinense Volume 2.Amsterdam.Retrieved8 May2015.
  9. ^"MelaleucaL. "APNI.Retrieved8 May2015.
  10. ^Barlow, B.A. (1998). "Patterns of differentiation in tropical species ofMelaleucaL. (Myrtaceae) ".Proceedings of the Ecological Society of Australia.15:239–247.
  11. ^Brown, Robert (1814).A Voyage to Terra Australis Volume 2.London. p. 548.Retrieved8 May2015.
  12. ^Craven, Lyndley (2006)."New combinations inMelaleucafor Australian species ofCallistemon(Myrtaceae) ".Novon.16(4): 468–475.doi:10.3417/1055-3177(2006)16[468:ncimfa]2.0.co;2.S2CID84723155.Retrieved8 May2015.
  13. ^"Callistemon- background ".Australian Native Plant Society (Australia).Retrieved8 May2015.
  14. ^abEdwards, Robert D.; Craven, Lyn A.; Crisp, Michael D.; Cook, Lyn G. (2010)."Melaleuca revisited: cpDNA and morphological data confirm that Melaleuca L. (Myrtaceae) is not monophyletic".Taxon.59(3): 744–754.doi:10.1002/tax.593007.JSTOR25677666– via JSTOR.
  15. ^Craven, Lyn A.; Edwards, Robert D.; Cowley, Kirsten J. (30 June 2014)."New combinations and names inMelaleuca(Myrtaceae) ".Taxon.63(3): 663–670.doi:10.12705/633.38.
  16. ^"Calothamnus".World Checklist of Selected Plant Families(WCSP).Royal Botanic Gardens, Kew.
  17. ^George, Alex S. (August 2015)."More Nomenclature Clutter"(PDF).Wildflower Society of Western Australia Newsletter.53(3): 7–9.Retrieved17 August2015.
  18. ^"MelaleucaL. "Endemia, New Caledonia.Retrieved25 January2018.
  19. ^Hawkeswood, Trevor J. (1980)."Jewel beetles as pollinators ofMelaleuca pauperifloraF.Muell. between Eucla (W.A.) and Koonalda (S.A.) ".The Western Australian Naturalist.14:238–239.Retrieved20 April2020.
  20. ^Campbell, A.J.; Maddox, C.D.A. (1999). Southwell, Ian; Lowe, Robert (eds.).Tea tree: The genus Melaleuca.Amsterdam: Harwood Academic. p. 169.ISBN9057024179.
  21. ^"Beesonia ferrugineus".scalenet.info.Retrieved13 July2023.
  22. ^"Myrtle rust".South Wales Government Department of Primary Industries.Retrieved29 June2016.
  23. ^Mazzotti, Frank J.; Center, Ted D.; Dray, F. Allen; Thayer, Dan."Ecological consequences of invasion byMelaleuca quinquenerviain south Florida wetlands: Paradise damaged, not lost ".Retrieved8 May2015.
  24. ^Langeland, K.A."Help protect Florida's natural areas from non-native invasive plants".University of Florida.Retrieved8 May2015.
  25. ^"Melaleuca quinquenervia".Smithsonian Marine Station at Fort Pierce.Retrieved8 May2015.
  26. ^Levitt, Dulcie; Lyon, Ken (1981).Plants and people: aboriginal uses of plants on Groote Eylandt.Canberra: Australian Institute of Aboriginal Studies. pp. 54–55.ISBN9780391022058.
  27. ^Williams, Cheryll (2010).Medicinal plants in Australia(1 ed.). Dural, N.S.W.: Rosenberg.ISBN9781877058943.
  28. ^Markham, Julie L. (1999). Southwell, Ian; Lowe, Robert (eds.).Tea tree: The genus Melaleuca.Amsterdam: Harwood Academic. p. 169.ISBN9057024179.
  29. ^ab"Tea tree oil".Drugs. 13 February 2023.Retrieved4 May2023.
  30. ^Carson, C. F.; Hammer, K. A.; Riley, T. V. (17 January 2006)."Melaleuca alternifolia(Tea Tree) Oil: a Review of Antimicrobial and Other Medicinal Properties ".Clinical Microbiology Reviews.19(1): 50–62.doi:10.1128/CMR.19.1.50-62.2006.PMC1360273.PMID16418522.
  31. ^O'Brien, Peter; Dougherty, Tony (2007).The effectiveness and safety of Australian Tea Tree oil(PDF).Barton, A.C.T.: RIRDC. pp. 9–12.ISBN978-1741515398.Retrieved19 August2015.
  32. ^Brophy, Joseph J.; Craven, Lyndley A.; Doran, John C."Melaleuca - Their Botany, Essential Oil and uses (Preliminaries)"(PDF).Australian Centre for International Agricultural Research. Archived fromthe original(PDF)on 28 May 2015.Retrieved19 August2015.
  33. ^Doran, John C. (1999). Southwell, Ian; Lowe, Robert (eds.).Tea tree: the genus melaleuca.Amsterdam: Harwood Academic. pp. 221–224.ISBN9057024179.
  34. ^Wrigley, John W.; Fagg, Murray (1983).Australian native plants: a manual for their propagation, cultivation and use in landscaping(2nd ed.). Sydney: Collins. pp. 351–352.ISBN0002165759.
  35. ^Brophy, Joseph J.; Craven, Lyndley A.; Doran, John C. (2013).Melaleucas: their botany, essential oils and uses.Canberra: Australian Centre for International Agricultural Research. pp. 34–35.ISBN9781922137517.
  36. ^"Joy [music]".

External links[edit]

  • Media related toMelaleucaat Wikimedia Commons
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