This article was published in The Fringe, August 2015
Lancewood - Horoeka
The Pseudopanax genus belongs to the Araliaceae family which in New Zealand includes the five-finger species, and overseas includes the common ivy and the Asian herbal remedy ginseng. Most Pseudopanax are endemic to New Zealand with one in Tasmania and perhaps two in Chile, depending on how closely the genus is defined. Several of the New Zealand species have been reclassified as Raukaua, a word derived from the Maori name for one of the species, raukawa.
Lancewood is clearly within the Pseudopanax family along with its closely related species P. ferox, P. linearis, P. chathamicus, and P. lessonii. While the first three are not common, being range-restricted, they all share the characteristic of having long narrow, toothed leaves. The last is also known as houpara or coastal five-finger and is common along northern coastlines. It also has the capacity to hybridise freely with lancewood as their habitats frequently overlap.
Lancewood is one of New Zealand's most easily recognised plants and yet probably it caused early botanists more confusion than most of their discoveries. Lancewood has such a distinctive form in its early growth period that it took a long time for botanists to make the connection between the one metre long downward-pointing leaves of the sapling and the much shorter wide-spreading leaves of the adult.
There are several stages that can be identified in the growth of a lancewood, from the round cotyledon leaves that emerge from the seed, through to some triangular juvenile, toothed leaves which elongate as the seedling grows into a sapling. Over the 20 years it might take before it flowers, a sapling first grows longer and longer, narrow leaves, then as maturity approaches its leaves get wider and shorter.
Eventually, when the sapling is about six metres tall, the first flowers emerge out of the growing tip as a 'terminal compound inflorescence'. This produces radiating groups of five arms called 'pedicels' which spread out like the ribs of an umbrella, and then generally subdivide into five more ribs (or 'umbellules') which terminate in five flowers. The symmetry continues as the flowers also display their floral parts in multiples of five. Five petals, five functional stamen on male plants, and the female flower is topped by five stigma which carry the pollen to the five ovaries, resulting in five seeds in one fruit, if all receive pollination. A fine example of nature's designs.
But why would a plant go to the trouble of having such different growth forms at different stages of its life? What caused such a strange growth habit? The best answer I know is that it is a defence mechanism against browsing animals. "But," you might say, "New Zealand had no mammals". Which is true, except that our birds, particularly moa, would browse and graze by tugging at the foliage until it snapped. Most of the divaricating shrubs developed a zig-zag branch network and little leaves hidden behind a twiggy exterior to deter moa. Lancewood, however, chose to create a tough leathery midrib with not much in the way of foliage on it, to repel hungry moa. Once the plant exceeded the height of the tallest moa it was then able to revert to a more normal leaf form and proceed to flower, safe in the knowledge that moa could no longer pose a threat to it.
Modern architecture and confined spaces are ideal for lancewoods which can provide an element of wonder and a striking artistic form to complement any building. Try a grove of them if you have the space and enjoy a variety of sizes for maximum interest. Enjoy.