A native super herb
The amazing powers of m¯anuka
When devoid of flowers, manuka ( Leptospermum
scoparium) is not much to look at, it’s true, but since this native shrub is smothered in blooms for many months of the year, it’s a plant well worth having in your backyard.
Manuka grows in virtually any kind of soil. It’s found in swamps, on sand dunes and in rocky spots across the country. It is fast-growing, and when in bloom, has a mild, sweet fragrance that’s extremely attractive to bees.
On the herbal front, manuka is a rongoa stalwart, with many marvellous medicinal qualities. Traditionally, an infusion from the leaves was drunk for kidney and urinary problems, and the vapour from the boiled leaves inhaled to treat colds and respiratory problems. Both the leaves and bark were boiled together, and the warm liquid rubbed over aching joints. Ash made from the bark was rubbed onto the skin to treat skin diseases. A decoction of the bark was also used as a sedative and mouthwash as well as for bathing sore eyes, and treating diarrhoea and dysentery.
History Dr WH Goldie
wrote of a treatment for burns and scalds in Maori Medical
Lore (1905): “As an emollient they used the white gum, called manna by the colonists, gathered from the manuka, or tea-tree.” Edward Frost, in Native Medicinal
Herbs (1930), also admired manuka’s healing properties: “A poultice of pounded titree berries applied to a flesh wound, being strongly astringent, would dry it up quickly, and greatly assist in healing.”
It’s reported that the seed capsules were chewed for stomach problems as well. I tried one myself once, but frankly, it’s not very pleasant. I can think of far tastier herbs for stomach issues, but until the Europeans arrived, such herbs were not available so whatever worked was the plant of the day.
Frost wrote again, in 1947, of the manuka berry’s healing powers. “I once saw a very bad adze cut on the instep healed in a very short time with a poultice of macerated manuka berries. The man was barefoot adzing down a post when a chip adhered to the blade of the adze and deflected it off the object causing a wide, deep gash in the foot. Women nearby, under the direction of an old man, immediately set about collecting these berries and pounded them on a flat stone applying a little water. When sufficient was obtained it was applied to the wound and the foot bandaged. In a little over a week it was healing splendidly and the cure was complete in a remarkably short time.”
Science These days, new studies
are focused on the medicinal properties of manuka honey and manuka essential oil rather than the plant itself, though the whole herb is still used to treat a long list of ailments, including gingivitis, diarrhoea, dysentery, irritable bowel syndrome (IBS) and stomach cramps as well as bacterial and fungal infections.
Indeed, the plant is antimicrobial, antifungal, anti-inflammatory, anxiolytic (reduces anxiety), spasmolytic, astringent and sedative, among other things. You can make your own antimicrobial, antifungal and anti-inflammatory salve by infusing the herb (all aerial parts) in oil and adding the infused oil to melted beeswax. When using the bark, peel off the outer bark first.
Interestingly, manuka in different locations around the country have different levels of active constituents, which can depend on soil, sun and other environmental factors.
Of greatest interest are the b-triketones in m¯anuka essential oil, which are believed to significantly contribute to its antimicrobial action. Studies show significant geographical variations affecting the composition of these oils. The oil from the East Cape chemotype is more active against gram-positive bacteria such as Staphylococcus, Enterococcus and Streptococcus spp. as well as antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus
aureus and MRSA. This is thanks to its high levels of b-triketones. In comparison, oils from other areas contain insignificant levels of b-triketones.
The concentration of b-triketones in m¯anuka oils ranges from less than 1 per cent to over 40 per cent.
When buying an essential oil, see if it has a rating. A 10+ rating means it has at least 10 per cent b-triketones; a 40+ rating means the oil is sourced from the East Cape region of New Zealand and contains at least 40 per cent b-triketones.
Manukaˉ in different locations around the country have different levels of active constituents, depending on soil, sun and other factors.
On the herbal front, mānuka is a rongoā stalwart, with many medicinal properties, from soothing burns to treating dysentery.
Non-b-triketone manuka oils are useful too. An aromatherapist may use a non-b-triketone manuka oil that has high levels of monoterpenes, for example. Monoterpenes can be used as a mucus membrane tonic, or decongestant, to ease nasal and other mucus membrane discomfort.
And if you want to use manuka as a fragrance, look for one that has high levels of Methyl cinnamate, which is again dependent on where the plant was grown. There are three areas in New Zealand where manuka has high levels of these oils. The highest cinnamate level was 23.9 per cent in the South Island, while the North Island average was 6 per cent, and the minimum 0.1 per cent.
In the garden Manuka ˉ is a fast-growing shrub
or small tree growing 3-4m high. Its white flowers are borne in profusion in spring and early summer (though there are many cultivars with red and pink flowers); even small seedlings will bear a flower or two. Leaves are small and prickly, which is one way to tell the difference between manuka and kanuka ( Kunzea ericoides): the leaves of kanuka are soft.
Manuka grows well in wet or dry sites, in exposed areas and is tolerant of infertile soil.
Unopened brown seed capsules can be collected throughout the year. As manuka is variable across the country, source it from your own area. Place the seed capsules in a paper bag and leave the bag in a warm, dry room until the seed is released. Sow the seed in a tray of seed-raising mix without covering. Water in well. Germination occurs within 10 days or so, depending on the temperature. Semi-ripe or hardwood cuttings can also be taken from March to May.