Wondering what the profuse white flowering trees are along Piha Road? They are olearias, New Zealand tree daisies. I have never seen such a display as this spring, with some hillsides in the Ranges, white with flowers.  Olearia are in the genus Compositae, thought to be the largest family of flowering plants globally. Which olearia of the many are the ones on Piha Road?

I suspect it is Olearia rani, or Heketara, which the botanist JT Salmon calls “the most beautiful of the New Zealand tree daisies.”

The other candidate is Olearia arborescens or Common tree daisy. Why do I think O rani?

Firstly, some of the trees along Piha Road are quite tall – O rani grows to 7.5 m, while O arborescens stops at 4m. While O rani bushes out on a stream bank or clearing, in the forest it grows up on a slender trunk then forms a crown. Salmon talks about O rani smothering hillsides and being visible as a display from some distance, and that is certainly so when you can see beyond the roadsides on Piha Road.

Secondly, the leaves of the trees on Piha Rd are lighter and broader, I think, that O arborescens. John Dawson in his book Nature Guide to the New Zealand Forest, says O rani’s leaves are like a smaller version of Rangiora and that was true of the trees on Piha Road.

I am willing to be proved wrong, so let me know if you have a different view s_coney@xtra.co.nz. Both varieties of olearia are quite common so there is no rarity value in the one or the other.

Olearia Rani, Piha Road, 5 October 2012