May in the forest with Chris Horne and Barbara Mitcalfe
Myoporum laetum, Ngaio
In my garden, one of NZ's fastest-growing trees, ngaio, lives up to its description, 'laetus', which means ‘happy’. Its glossy, dark olive-green, oil gland-dotted leaves c. 80 mm long by c. 40 mm wide, are the picture of health, and tūī think the bright mauve, fingernail-sized fruit are “just the berries”! But beware, all parts of the plant, especially the leaves, are to some degree poisonous to humans and stock. Tūī however, must be immune, because at this time of the year they spend all day a-chortle, gorging on the fruit and not succumbing to anything worse than melodious drunkenness.
Ngaio has dark brown, deeply- furrowed bark, and small clusters of white flowers c. 20 mm in diameter, each with a few tiny purple dots. The leaf buds are typically black-brown and sticky – in fact if they aren't, you've probably got an unwelcome Aussie look-alike instead, called boobialla.
Boobialla is a member of the Myoporum genus, its botanical name is Myoporum insulare. Boobialla is unwelcome in NZ, because unfortunately it readily hybridises with our NZ ngaio. Probably mistaken for NZ ngaio, it was propagated and planted extensively by many local nurseries and councils in the 1970s and 80s, particularly on the west coast, north of Wellington. As a result, it has become a pesky weed in Pukerua Bay and Queen Elizabeth Park, Paekakariki. Remember - a good way to tell the difference between ngaio and boobialla is to look for those black-brown, sticky leaf buds on NZ ngaio.
A well-grown ngaio can reach to c. 10 m in height, with a rounded, spreading crown. Found in the Kermadecs, the Three Kings and the North, South and Chatham islands, it is usually coastal but can also grow in warm sites further inland. The only other Myoporum species in the NZ flora is a sprawling one with larger leaves, Myoporum rapense sub-species kermadecensis.
Like many other NZ native trees, ngaio is a handy source of rongoa (medication) in the hills. The toxin, ngaione, is in fact the medicine. It is concentrated in pale, see-through oil glands in ngaio’s leaves. Just as kawakawa leaves do, a hot poultice of shredded ngaio leaves will greatly hasten the healing of a septic wound. Trampers also appreciate that the juice of bruised ngaio leaves, when rubbed on exposed arms and legs, successfully deters sandflies and mosquitoes.