| Leptospermum scoparium | |
|---|---|
| Leptospermum scoparium foliage and flowers | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Myrtales |
| Family: | Myrtaceae |
| Genus: | Leptospermum |
| Species: | L. scoparium |
| Binomial name | |
| Leptospermum scoparium J.R.Forst. & G.Forst. |
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Leptospermum scoparium (Manuka or Tea tree or just Leptospermum) is a shrub or small tree native to New Zealand and southeast Australia. Evidence suggests that L. scoparium originated in Australia before the onset of the Miocene aridity and dispersed relatively recently from Eastern Australia to New Zealand.[1] It is likely that on arrival in New Zealand, L. scoparium became established in limited edaphically suitable areas until the arrival of Polynesian man whose fire and forest-clearing brought about the low-nutrient-status soils for which it was pre-adapted in its homeland. It is now found throughout New Zealand but is particularly common on the drier east coasts of the North Island and the South Island, and in Australia in Tasmania, Victoria and New South Wales. Manuka (from Māori 'mānuka') is the common name used along with 'Jelly Bush' and 'tea tree' in Australia and to a lesser extent also in New Zealand. This name arose because Captain Cook used the leaves to make a 'tea' drink.[2] The common name "Tea Tree" is also shared with the related Melaleuca tree of Australia suggesting that both were used to make tea by Captain Cook.
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It is a prolific scrub-type tree and is often one of the first species to regenerate on cleared land. It is typically a shrub growing to 2–5 m tall, but can grow into a moderately sized tree, up to 15 m or so in height. It is evergreen, with dense branching and small leaves 7–20 mm long and 2–6 mm broad, with a short spine tip. The flowers are white, occasionally pink, 8–15 mm (rarely up to 25 mm) diameter, with five petals. This species is often confused with the closely related species Kānuka – the easiest way to tell the difference between the two species in the field is to feel their foliage – mānuka leaves are prickly while kānuka leaves are soft.[3] The wood is tough and hard.
The wood was often used for tool handles. Mānuka sawdust imparts a delicious flavour when used for smoking meats and fish. It is cultivated in New Zealand for the honey and pharmaceutical industries.
Mānuka products have high antibacterial potency for a limited spectrum of bacteria and are widely available in New Zealand and Australia. Similar properties led the Māori to use parts of the plant as natural medicine. Mānuka seed extract has exhibited antimicrobial action against S. aureus and E.coli.
Kakariki parakeets (Cyanoramphus) use the leaves and bark of mānuka and kānuka to rid themselves of parasites. Apart from ingesting the material, they also chew it, mix it with preen gland oil and apply it to their feathers.[4]
Mānuka honey, produced when honeybees gather the nectar from its flowers, is distinctively flavoured, darker and richer in taste than clover honey and has strong antibacterial and antifungal properties.[5][6] The finest quality mānuka honey with the most potent antimicrobial properties is produced from hives placed in wild, uncultivated areas with abundant growth of mānuka bushes. However, only a very limited number of scientific studies have been performed to verify its efficacy.
The University of Waikato in Hamilton, New Zealand has formed the Waikato Honey Research Unit to study the composition of honey and its antimicrobial activity. The Active Manuka Honey Association (AMHA) is the industry association that promotes and standardizes the production of mānuka honey for medical uses. They have created the Unique Manuka Factor (UMF)[7] standard which grades honey based on its anti-bacterial strength. Because of its antimicrobial properties, Manuka Honey is added in small amounts D-Dartos Oral Suspension and other products. In January 2008 Professor Thomas Henle, Dresden University of Technology (Germany)[8] identified methylglyoxal as the active compound in Manuka honey. This is now shown on products as MGO Manuka honey. For example, MGO 100 represents 100 mg of methylglyoxal per kilogram.[9]