Northwest Nelson

May 19, 2014

The marble outcrops, karrenfeld and boulder-strewn slopes of Takaka Hill host a number of distinctive plant species that I was keen to view in the wild, as part of a research trip to northwest Nelson. One of the plants that I was most interested in seeing was Hoheria ovata (in the centre of the photograph below) – a small tree with conspicuous displays of white flowers that is native to northwest Nelson and the West Coast.

We have specified a significant quantity of this plant in a Nelson project for a quality that many might consider to be of peripheral interest – the trunk (pictured below). In response to a shelter belt of willows, we needed to create an understorey element that repeats the character of the willows, thereby providing the sense of a woodland that extends into the property (rather than the jarring line of a shelter belt, which can be desirable in many instances but not in this context).

Another resident of Takaka Hill is the limestone kowhai, Sophora longicarinata, which is only found in the Nelson region and western Marlborough. This attractive species (which is shown below, centre) differs from other kowhai by being more inclined towards a multi-trunking habit and possessing relatively long, delicate leaves on which the leaflets look somewhat like droplets of water.

The upper sections of the hill have a much drier feel to them, due to the shallow soils and wind exposure. In parts, a species that we often plant for informal structure, Melicytus obovatus, forms compact, bright green shrubs within marble karrenfeld. At the end of one of our days, we drove to Whanganui (Westhaven) Inlet – an enormous winding inlet with majestic native forest descending to the shore along much of its length.

At the old Westhaven wharf, an ad hoc jetty has been installed at some stage for recreational users. Driven by the elements that it needed to connect and be built off, this structure (above, right) had an intriguing form – particularly the way in which the timber jetty meets the wedge of pre-existing concrete.

Since reading about Whanganui Inlet in Geoff Park’s remarkable book, Nga Uruora, I have wanted to come to this place. One thing that I was not aware of (but which was pointed out to me by David Straight) is that the inlet has a network of impressive causeways that are retained by stone. Whilst stopping by one of these causeways close to dusk, we spent time observing a kotuku (white heron) fishing in the channels at low tide.

On the opposite coastline fom Whanganui Inlet (towards Abel Tasman Park), a striking manmade port juts out from the limestone cliffs at Port Tarakohe. In addition to providing port facilities for the quarrying of lime rock and cement, the port is a welcome refuge for sailors who are presented with the changeable weather conditions and lack of sheltered bays as one rounds Separation Point.

To the west of the famous Farewell Spit, Wharariki Beach sits near the northern point of Golden Bay. Most visitors to this beautiful beach are attracted by the rolling white sand dunes and seal pups that play near the shoreline. An additional drawcard is the range of native plants that reside among its dunes or on the cliffs that run down to the beach.

I was particularly eager to see a creeping form of Coprosma which is sold as Coprosma ‘Wharariki’ (the bright green shub creeping at the base of the photograph above), and which bears similarities with Coprosma neglecta (and the complex of forms associated with that species). Amongst the plethora of often dull groundcover forms of Coprosma (many bred from hybridisation), this plant (which is grown by Titoki Nursery) has an especially elegant growth form, as well as an attractive dark green hue.

It was interesting to note that (similar to Coprosma ‘Hawera’) this form occupies the consolidated sandstone cliffs (shown below), whilst Coprosma acerosa lives primarily within the dunes (although I also observed C. acerosa growing on a cliff amongst C. ‘Wharariki’).

On this trip we took the long drive to Cobb Valley, a place that I had visited 10 years beforehand. Perhaps the plant that is of the greatest local significance to this area is Pittosporum dallii; an unusual, nationally threatened small tree that is only found in northwest Nelson. The image to the left (below) shows a mature specimen emerging from scrub on Cobb Ridge, whilst the photograph to the right (below) demonstrates the dark, serrated leaves that are one of the features that distinguish this beautiful plant from other NZ species of Pittosporum.

Part of the reason for the level of access through to this isolated valley (in addition to mining) is that it has been adapted for energy generation – including the formation of the lake (above, left) by a dam, and the piping of enormous water flows through the hydro station pictured below. This makes for an impressive sight where the water rushes out of the exit gates in the station, to continue its journey via the Takaka River towards the coastline.