This article was published in the Titirangi Tatler, March 2011
Mamangi or Tree Coprosma
Is there a native tree so widespread around Auckland, but so little-known as mamangi?
Distributed throughout the coastal lowland forests of the northern half of the North Island, Coprosma arborea is often the dominant tree in the mid-canopy. As most of the taller old-growth trees have been felled for timber, fence posts or firewood, it leaves mamangi as the canopy in many areas of cut-over forest. Frequently, it is a major component of the sub-canopy in kauri forests.
It is the unusual quality of light that the Coprosma arborea creates when it is dominant in the forest that first draws your attention when out tramping. Glancing up you will see the characterisic light filtering through the bronze leaves. On the ground, the uniform leaf litter indicates the density of trees overhead and clearly reveals the predominant nature of the mamangi .
A handsome tree up to 10 or 12 metres in the forest, it can have a trunk diameter of half a metre. Of course, in your garden, it will not reach those dimensions. Without the need to compete for light, forest trees in an open garden will normally only reach a third of their forest height.
The curiously-coloured leaves are yellow-green above and bronze-red below. The leaf blade is 8 x 4cm and has tapering wings along the stem which are particularly prominent in the juvenile plant. Coprosma flowers are quite indistinct with the male and female on separate trees. The translucent, glassy white fruit is 8mm in diameter and much-loved by birds. The fruit is technically a drupe with two woody seeds, just like its close tropical relative that provides our coffee beans, Coffea arabica. Frequently eaten before they are ripe, the copious fruit are widely-distributed by birds, resulting in dense clusters of seedlings growing under favourite bird perches.
Mamangi was, and still is, confused with the much smaller shrub Coprosma spathulata which also has a winged stalk or petiole. Easily distinguished when in fruit, Coprosma spathulata has larger dark red to black fruit.
Perhaps we can be excused for not noticing or recognising mamangi, as it took the early botanists 100 years to sort out its status before it was described by Thomas Kirk in 1878.
Look around your garden and check for the pest weed species that will have inevitably invaded, and consider replacing them with a Coprosma arborea.
Weeds that are revealing themselves at this time of year (March) are ginger, moth plant, agapanthus and the ubiquitous tobacco weed. Get them now before they deliver another crop of seeds to lurk in your soil.