Melaleuca quinquenervia is a broad leafed paperbark tree which grows naturally along the east coast of Australia North of Sydney, to South Central Queensland, in New Caledonia, and Southern New Guinea (PNG and Irian Jaya). It is found as an introduced species in Madagascar; many African nations including Benin, Egypt and Tanzania; in the North American states of Florida, Louisiana and California; and, in a number of Caribbean nations.
In Australia and New Guinea, it occurs in coastal swamps and hinterland waterways below 100m but in New Caledonia it can occur in large stands up to 1000m.
As an introduced species M. quinquenervia exhibits prolific seed production, many times more than specimens originating in Australia (CABI invasive species compendium). It was introduced to North American on numerous occasions after 1886, mostly, but not exclusively, from Australia. It was used in landscape gardening and forestry projects and as an exotic garden feature. Originally hailed as a positive introduction the species had become by the mid-20th century, a naturalised invasive weed, threatening native ecosystems in important natural habitats such as the Florida Everglades National Park. It now occupies at least 20,000 ha in Florida alone (Dray et al, 2006). The majority of current research on M. quinquenervia relates to weed control procedures and information relating to weed control, which is a shame, as it makes some very nice essential oil!
Commercial cultivation of M. quinquenervia is believed to have commenced in Madagascar in the 1880’s. (Dray et al, 2006). The essential oil of M. quinquenervia produced in Madagascar and New Caledonia is traded as Niaouli Oil and consists primarily of viridiflorol, 1,8-cineole or both. The essential oil of Melaleuca quinquenervia produced in Australia consists primarily of Nerolidol (>90%) or Nerolidol (>30%) and Linalool (>35%) and is commonly traded as Nerolina oil.
Classification of essential oil chemotypes for standardisation of M. quinquenervia is problematic as common constituents occur in a range of relative proportions. This results in different authors classifying conflicting numbers of chemotypes. To add to this confusion is historical taxonomic confusion between other broad leafed paperbarks such as M. leucadendron and M. viridiflora.
Ramanoelina (2008)(1994) examined the chemotypic range of Melaleuca quinquenervia oils in Madagascar and described 4 distinct chemotypes: viridiflorol (>50%), nerolidol (>85%), 1,8-cineole (>50%), viridiflorol (20%)/cineole (20%).
Ireland (2002)reported there to be four main oil types: oil rich in 1,8-cineole (30-65%); oil low in 1,8-cineole (1-30%) with varying substantial proportions of hydrocarbons and other oxygenated compounds such as viridiflorol and globulol; oil predominantly E-nerolidol (90%); oil predominantly E-nerolidol (65%) but with substantial proportions of linalool (35%)
Moudachirou (1996) identified three chemovarieties from Melaleuca quinquenervia grown in Benin. One with a high content of 1,8-cineole (48%) and a smaller amount of viridiflorol (17%), another with about equal amounts of the same two compounds and a third variety rich in viridiflorol (48%) with 1,8-cineole (12%) as the second most important constituent.
Brophy and Doran (1996) describe two chemotypes occurring in eastern Australia, distinguished by being composed primarily of either viridiflorol/1,8-cineole or nerolidol/linalool. Further chemotypic differentiation appears to be based on two or three sub-classifications made on the relative proportions of the respective pairs (ie, 1) low cineole:high viridiflorol, 2) high cineole:low viridflorol, 3) even amounts of cineole:viridiforol.
M. quinquenervia can contain other components in significant proportions including B-caryophyllene, a-terpineol and a-pinene which will serve as useful indicators for chemotypic differentiation.
Doran et al (2007) found in their screening of Myrtaceous species for essential oil production in North Queensland that of the species and chemotypes evaluated, M. quinquenervia showed potential for commercial production of trans-nerolidol. “It had a very high survival rate (96%) and yields could be expected to improve dramatically from the average 100 kg/ha per harvest achieved in these trials with further research into selection of seed source, control of insect damage and breeding for genetic improvement”.
REFERENCES:
CABI Invasive species compendium (http://www.cabi.org/isc/datasheet/34348)
