Subterfuge

On the return leg from site visits to two new projects in Northland, Logan and I stopped at Rangitane Peninsula (near Kerikeri) to observe a species that we frequently specify within our designs, Pittosporum pimeleoides, in one of its most significant extant populations.

Within designs, this rare shrub offers a fine texture (on a compact growth form), in addition to night-scented flowers in winter. One point that we were aware of before visiting this habitat was the considerable variation that Pittosporum pimeleoides exhibits in both leaf shape/size and growth form.

This was in full effect within the kanuka woodland at this headland, with some individuals bearing extremely narrow leaves (similar to Leptecophylla – syn. Cyathodes – juniperina) and others possessing much more substantial foliage – to the extent that they seem like completely different species. Growth form varied from taller, upright shrubs to low-weeping forms.

This morphological plasticity is a trait exhibited within the genus Alseuosmia; whose members throw out all manner of strange variations (which often appear to mimic non-palatable species).

In the case of Pittosporum pimeleoides, its many permutations seem to mimic other members of this kanuka woodland community, such as Leucopogon fasciculatus, Leptecophylla juniperina and kanuka itself (Kunzea robusta) – as shown in the image below, right.

There are undoubtedly intelligent things to be deciphered about convergent evolution here, but our thoughts were primarily focussed on just what Pittosporum pimeleoides is playing at. And does the anonymity that comes with this similarity of form assist it with environmental pressures ?

Whatever is going on, the magnitude of variations that we observed further opens one’s eyes to the possibilities of horticultural selection with this intriguing species – which will be the subject of an upcoming plant profile on the O2 website.