Discovery in Riverhead Forest Has Botanists in a Spin
Many moons ago the 2007 NZPCN Life Time Achievement Geoff Davidson, founder of Oratia Native Plant Nurseries, and major mover in plant conservation helped protect a small indigenous forest remnant near Riverhead, north-western Auckland. In early November last year Geoff took a short stroll through that particular forest, and was surprised to find what he thought was Jovellana repens. As the plant was sterile, and there are no records of Jovellana repens north of East Cape and Mt Pirongia known, Geoff took a small piece and grew it on. In late November I was shown the find, and immediately recognised that it was not a Jovellana but had some resemblance to a Parahebe or Veronica. However, without flowers or fruits little more could be done, and so it remained an unresolved problem until, not long after Christmas it flowered. The white flowers with deep magenta nectar guides, and enfolded corolla lobe bases had a remarkable resemblance to Parahebe lanceolata, but the bright green, orbicular-spathulate leaves, extremely hairy stems, petioles, leaf margins, peduncles and pedicels were not typical of that variable species, nor the prostrate, widely creeping, semi-herbaceous growth habit. Perplexed I suggested Geoff take images, and these I forwarded to Professor Phil Garnock-Jones of the Department of Biological Sciences, Victoria, University of Wellington.Phil was not long in replying. To him the foliage was reminiscent of the subalpine to alpine, North Island endemic P. spathulata but the flowers were more typical of P. lanceolata. Could it be a hybrid he wondered? Certainly it was distinctive and well worth further investigation. Samples were dually processed and sent to the University of Auckland for DNA sequencing using two chloroplast markers (trnL and rbcl) and one nuclear (ITS). Root tips were also sampled for a chromosome count. Another more obvious problem was to see it in the wild. Thus in late January accompanied by Geoff Davidson, Jeff McCauley (Head Propagator, Oratia Native Plant Nurseries) and Dr Rhys Gardner (Research Associate, Auckland Museum Herbarium) I set out for Riverhead Forest.
January was an incredibly dry month, and the forest remnant was suffering. Everywhere the forest floor was carpeted with fallen, wilted, canopy tree leaves, and the shrub tier was tinder dry, and mostly dead or dying. Several hours intensive searching found no Parahebe, leaving all concerned bamboozled as to its fate. Luckily Geoff had managed to propagate another plant, and rooted pieces were also sent to Phil Garnock-Jones for cultivation, study and as a further safeguard.
In early March the DNA results were in. All three DNA markers told much the same story, the plant, now dubbed Parahebe “bamboozle” was indeed allied to that genus, or, if you prefer the broader based concept, part of the Parahebe Clade of Southern Hemisphere Veronica. Close relatives were not forthcoming, with relationships to the New Guinea Parahebe strongly indicated in some portions of sequence and there were also links to Hebe, Chionohebe, New Zealand Parahebe, and Hebejeebie in others. In mid March, Associate Professor Brian Murray (Department of Biological Sciences, University of Auckland) obtained clear counts of 2n = 40 chromosomes – another oddity in Parahebe, with that number being known in the New Zealand species otherwise only from the apparently unrelated P. decora. However, that number is typical of Hebe.
Research is now underway to determine whether Parahebe “bamboozle” merits formal description. While that’s underway we only hope that more plants will be found in the wild soon!
Posted: 21/03/2008