One of the trees we are planting out at Manawa Karioi this winter is Mānuka or tea tree (Leptospermum scoparium). Everyone knows of Mānuka, although it’s easily overlooked as a relatively small tree, not a forest giant, and it’s not a major species in our more notable forests. But it is one of Aotearoa New Zealand’s most remarkable small tree species. Let’s take a closer look at it.
Mānuka is one of about 17 species of the Myrtaceae or myrtle family, a large family of some 3000 species of trees, shrubs and vines found mainly in tropical and warm temperate countries around the Pacific Ocean, but also including species in the West Indies and Europe. In New Zealand, myrtle family species include the pohutukawa and all the wonderful rata (Metrosideros) trees and vines, as well as Mānuka, its close relative Kānuka (Kunzia ericoides), and a few other related species. So Mānuka is in good company among its myrtle family members.
Mānuka has shortish, spiky needle-like leaves and pretty white spreading flowers. These grow in such profusion that Mānuka-covered hillsides can look as though they have a coating of snow. The withering flower reveals a broad and very hard five-valved capsule which is fire resistant. Take a close look at those capsules – they are very beautiful close-up.
Mānuka must be one of the most variable and adaptable of our native plant species. It grows in habitats from sea level to sub-alpine, can tolerate burning summers and snowy winters, arid hillsides and boggy hollows, fertile and barren soils. It is one of the first woody species to colonise landslide scars and other bare areas in the forest. You often see it on road cuttings. It grows as single trees up to more than 6 metres high, or as extensive thickets, sometimes only 20 or 30 centimetres high. This huge variety of forms is all contained within the one natural species, although many beautiful horticultural varieties have been bred, and widely admired in gardens all over the world.
Perhaps the most characteristic growth form of Mānuka is extensive thickets of often dense scrub about 3-5 meters high, sometimes forming an unbroken canopy, sometimes together with the slightly taller Kānuka. These thickets thrive for many decades until very gradually changing into more heterogeneous forest stands as new species slowly become established in the canopy. The thickets often grew up on farmland as less fertile or less accessible pastures were abandoned from extensive grazing, for example in parts of the Wairarapa and the East Coast. For farmers trying to “tame” nature, the scrub was seen as a curse, often burnt, crushed or hacked down to make way for new pasture (often no more successful than the old) or for pine plantations.
Mānuka has many uses, both in times past and now. In the past, it was an important medicinal plant for Māori; preparations from the leaves and bark were used to reduce fever, treat colds and as sedatives. In colonial times tea was truly brewed from its leaves and the very hard fragrant red wood was always highly regarded for fencing and for tool handles, and especially as a firewood fuel. But for now, Mānuka honey is the most valuable use.
A component chemical called methylglyoxal has known antibacterial properties and Mānuka honey is used externally as a wound dressing or eaten to reduce the risk of infection. There is debate about just how specific the medical benefits are, but few would deny the scrumptiousness of the honey. We can only hope that Mānuka and related species are not decimated by the newly arrived myrtle rust disease and other pathogens.
It’s ironic that the same Mānuka stands that were reviled and devastated only 20 years ago, are now valued so highly and actively managed as the food source for an industry that is seen as the saviour of many hill country districts. At Manawa Karioi Mānuka is not quite such a star, but it’s a versatile and much loved species for planting in various locations, whether on those exposed upper spurs, around boggy areas or around the beehives.
Written by Paul Blaschke.
Working bee Sunday August 20.
We depart at 1pm from the interpretation board shelter at the Tapu Te Ranga Marae carpark, signposted at the end of Danube St, Island Bay.
We will be going ahead rain or shine; wear good shoes and bring a jacket. Gloves, tools and plants are provided.
Planting will be around the beehives area, and will involve manuka and a number of locally rare shrub and small tree species. We finish planting around 3 - 3.30pm.
After planting we will go to the wharekai at the marae for tea and biscuits.
If you arrive late and can't find us, call 0221 277361.
A tree enthusiast and an ex-resident of Island Bay. Vanessa brings her digital skills to the volunteer team at Manawa Karioi - one of the oldest reforestation projects in Wellington.
With over 17 years experience volunteering with Manawa Karioi, Ross has a detailed knowledge of the project.
Paul Blaschke is an environmental consultant and part-time university lecturer. He loves living and working in Wellington’s southern suburbs, whether in the Owhiro catchment, the Town Belt near his home, or on the slopes at Manawa Karioi.
Chris and his partner and their 3 children were at the dawn planting of the first tree in 1991. He has maintained his involvement in the project ever since and gets great satisfaction now from seeing how much the trees have grown and how the associated native ecosystems have developed over those 26 years. Chris emphasises that providing tracks to enable the public to enjoy Manawa Karioi, and carbon sequestration, are both integral parts of the project.