Pennantia baylisiana
New Zealand's rarest tree —
its discovery and propagation

Reproduced from an article by Professor G. T. S. Baylis

From The New Zealand Garden Journal (Journal of the Royal New Zealand Institute of Horticulture), Vol. 2, No. 1, March 1997, pp. 12-13.

T. F. Cheeseman was an early Director of the Auckland Museum. He was also the first botanical explorer of the Three Kings Islands. On his visits in 1887 and 1889 he had only a few hours ashore, yet he found six new plants. A more thorough search was clearly warranted but it was not until 1945 that the Museum arranged for a scientific party to camp on the main island. I was the botanist.

In these clumps such things as puriri, mahoe and mangeao persisted and I soon found the liane Tecomanthe speciosa and the rangiora with a corky trunk like a cabbage tree - Brachyglottis arborescens. The last little grove that I investigated lay near the highest point of the island down a scree of boulders about 200m above the sea. I was drawn to it by what looked like a karaka. I was soon gazing upon it in disbelief since a third find seemed too much to expect. But this was no karaka - its leaves were larger and recurved strongly in the sun, its bunches of small green flowers sprang from the bare branches below the leaves and there were no big berries - indeed none at all.

Dr W. R. B. Oliver, our last true biologist equally authoritative about animals or plants was anxious to identify my finds and I sent them to him. Lacking time and experience, I feared I might blunder by getting a family wrong. This danger proved real indeed, for Oliver himself put the pseudo-karaka in the Anacardiaceae, which is close to the karaka family, whereas had I been able to send fruits he would have realized that the resemblance to karaka is misleading, the proper family being Icacinaceae to which Pennantia belongs.

It was a European botanist working with herbarium sheets who realised that the Three Kings specimens were Pennantia: indeed concluded that the tree was just a stray P. endlicheri from Norfolk Island. But herbarium sheets don't tell all - thicker leaves recurving curiously in the sun, stouter stems and flowers on leafless branches rather than at the ends of twigs so distinguish the Three Kings tree, that the two have little resemblance. So when our Flora is next revised either the definition of Pennantia will be broadened to accommodate cauliflory (flowers arising on old wood) or Oliver's genus Plectomirtha will reappear as a member of the Icacinaceae. The former seems the wiser course as P. baylisiana does occasionally flower at a branch tip. Moreover, the objective of taxonomy is to synthesise and there is no synthesis when a species has a genus to itself.

Propagating this lone and sterile tree, not in the best of health because of insect damage, seemed urgent. There was a detachable shoot at its base which took root in a damp sheltered place in my Dunedin garden and is now very like its parent with four slender trunks. But its canopy trimmed by occasional frost rather than repeated salty gales is taller (7m).

While I was unsure that this shoot had really rooted, I was worried by failure both at the Plant Diseases Division at Mt Albert and at Duncan and Davies, New Plymouth to strike cuttings from the crown. I asked George Smith the chief propagator at New Plymouth what I might do to provide better cuttings. "Cut the tree down" he said, and while I shuddered at the thought he explained that he was confident about rooting shoots from the stump. But would there be any? Well, the tree had four trunks so I dared to sever one. A year later the shoots were there, the Naval launch on which I was a guest gave them a quick passage to New Plymouth which happened to be its next port and Mr Smith soon placed the survival of "Plectomirtha" beyond doubt.

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