From the outside, it can be difficult to understand the reasons that certain species become threatened. In the case of kōwhai ngutu kaka (Clianthus maximus), the collapse towards its current tenuous state was swift and dramatic, falling from a wild population of over 1000 plants to fewer than 180 plants in the space of a few years.
In early October, I travelled to the East Coast/Tairāwhiti to take a closer look at plant communities from this part of New Zealand, including seeing C. maximus in the wild for the first time. As we moved our way through these landscapes, I was fortunate to be able to absorb some of the vast knowledge and familiarity that my friend, Graeme Atkins, has accumulated over many years of tirelessly working to preserve the natural heritage of the region.
Whilst checking on two of the most significant remaining sites for ngutu-kaka, Graeme recounted how the movement of pest animals through such landscapes (notably deer and goats in this context) acts as a driver for catastrophic change for certain plants – especially palatable species like C. maximus. Graeme has a rare combination of indepth botanical knowledge and a profound practical understanding of the very direct way in which animals and plants occupy landscapes (whether as friends or foe to native ecosystems).
The steep-sided, relatively high hillsides of Waimahuru (near Tokomaru Bay) were the location of the ngutu kaka sites that we were visiting. At the first site, nature was actively demonstrating one of the myriad threats that Clianthus maximus must contend with, as a large infestation of kōwhai moth caterpillars was stripping the foliage (an issue that has subsequently been dealt with successfully).
Despite the unwelcome influence of these caterpillars, this population was very interesting for what it showed of the habitat and growth form of ngutu kaka. The slip face on which the plants grew (which is situated in the middle of the hillside in the photograph below) effectively acts as a clearing within the surrounding forest, in which certain light-demanding species find opportunities to establish themselves.
One conspicuous aspect of C. maximus‘ growth habit was the similarity of its lax, arching branching structure to that of tutu (Coriaria arborea), which grows in considerable numbers within the same community of plants. This tendency towards a multi-branching, reaching growth form seemed to me to be especially suited towards maintaining a foothold on open, steep, unstable slopes, as is the manner by which ngutu kaka layers itself into the ground from these long stems (as pictured above, right).
Another feature of the reserve is the relative abundance of one of our most beautiful flowering species, Pimelea longifolia, which is pictured below. In most places where I have come across this elegant white-flowering shrub (with the exception of Mt Burnett), it occurs in fairly small numbers; an observation that is perhaps borne out in its current threat ranking – in which it is classified as ‘At Risk – Declining’.
Other species of interest were Chionochloa flavicans, a commonly-planted native tussock from the eastern North Island (pictured below, left), and Senecio rufiglandulosus, a native herb with spectacular yellow flowers (shown below, right). The latter was collected in flower by Banks and Solander on one of their earliest days ashore botanising, at Anaura Bay on 21 October 1769.
Due to our work on the design for the 1769 Garden at Longbush Ecosanctuary in Gisborne, I had timed this trip to coincide with their first days in Aotearoa (in the vicinity of where Gisborne now stands), as it was interesting to take in some of the impressions that they absorbed at that time – such as the flowering of kōwhai along this stretch of coast.
Upon working our way over to the second ngutu kaka site, we were met by the gratifying sight of Clianthus maximus in full bloom (pictured below), with no offending caterpillars on the scene. After many years of wanting to see this beautiful shrub in the wild, it was very civil of C. maximus to put on its best show – to go along with a day spent amongst a wide range of fascinating plant communities (including a surprising array of native orchids in bloom).