Realms of Raukawa
The genus of Raukaua currently encompasses six species in Araliaceae family. The natural habitats of these species range from Chile, Argentina, Tasmania and New Zealand. These countries would have all been connected as part of Gondwanaland before it broke apart 180 million years ago. Once placed in the Pseudopanax genus, new research is showing that our Raukaua may be more closely related to Schefflera. New Zealand has three species, R. anomalus, R. edgerleyi (raukawa) and R. simplex (haumakōroa).
The genus name comes from a latinised version of Raukawa, the Māori name for R. edgerleyi. A prized tree for its fresh aromatic oil released by crushing the leaves, this scent was used to infuse shark oil perfume. This alluring perfume was responsible for the union of Māhinaarangi and Tūrongo which brought together Tainui and East Coast families. The scented tree became the name of their son, the ancestor of Ngāti Raukawa. It is scarce across its range, due to relatively small seed production and its palatability to browsing pests. Juveniles start out beautifully narrow with deeply lobed leaves and often occur epiphytically on tree ferns. These leaves change dramatically in the adult stage to an elliptical, glossy leaf and are not toothed like adult R. simplex. On Mt Kaukau in Wellington, it appears to share an affinity for the understory of Pinus radiata (pine) forest. Potentially, the pine is offering a similarly acidic soil condition to native coniferous forests comprised of rimu or mataī in which it evolved. Although difficult, it is worthy of cultivation for its tropical appearance, scented leaves and for conservation. It prefers damp soils, semi-shade and can grow to 10m tall. The second species haumakōroa shares many attributes with R. edgerleyi, but the main differences include unscented leaves, serrate adult leaf margins (resembling Pseudopanax species) and a smaller height of 8m. It can be found 500m higher in elevation and will grow in montane shrubland associations. In my experience of Wellington’s flora where there is one Raukaua tree species, the shrubby R. anomalus is not far away.
R. anomalus is an a rather anonymous shrub and to many, perhaps not very interesting. But a divaricating araliad makes an aptly named anomaly in a family of 1500 species, most being larger-leaved tropical plants. The presence of strong, dry winds and snow in New Zealand are quite adept at defoliating plants. It takes little imagination to understand why this plant has developed small leaves and a tangled form to protect itself from these conditions. Local variations in micro-climate can change the growth habit in individuals just 100m away. On ridgelines and above the tree-line it stays a compact mass with purple-grey to orange stems, but under canopy it takes a looser form with broader leaves. These sheltered forms elude to a possible divergence from R. simplex in a milder epoch. Like many of our divaricate shrubs in New Zealand, R. anomalus also shares a confusing resemblance to many other species. Whilst divaricate identification is easier, it is akin to the difficulty the mycology field has with identifying LBM’s (little brown mushrooms). In this case it is SLTS (small-leaved tangled shrubs), which makes for a worse looking acronym on paper. Most comparisons to R. anomalus are Melicope simplex but this has citrus scented leaves or Melictyus micranthus, which has a light green blotch at the leaf base. Where for R. anomalus, the dark brown blotch at the leaf base can be a good identifier if present . If you have an exposed spot consider planting it as a hedge, at Belmont Trig (pictured below) it has been trimmed along a walking tracking and seems to handle it well.
For enthusiasts of SLTS, grab a copy of Hugh Wilson and Tim Galloway’s ‘Small-leaved Shrubs of New Zealand.’
