North to Northwest

December 20, 2015

Over the course of the last 2 years, we have spent a considerable amount of time in the Nelson province, whilst preparing the design for (and installing much of) a project near Nelson. As I have written before, this has provided me with a great springboard for looking into the diverse range of plants and ecologies that occur in this part of the country. Of the many places that I have been to during this period, I had not yet found the opportunity to visit two relatively isolated mountains (Mt Burnett and Hoary Head) that contain a number of endemic species.

The first plant that we went to see was Clematis marmoraria, which makes its home on the neighbouring peaks of Hoary Head and Crusader. I had booked my flights for this weekend in the hope that we would see this tiny suckering species in flower, and C. marmoraria did not disappoint, with several plants in full bloom on the day that we went to Hoary Head (including the specimen pictured below).

Clematis marmoraria derives its specific epithet from the geology of the places that it inhabits (from ‘marmor’, the Latin word for marble). It grows within the fissures on marble outcrops, sometimes extending no further than the gaps through which its suckering stems creep (as shown below, in the centre of the photograph), and in other cases, trailing through small shrubs. It is difficult to tell whether the confinement of its foliage within fissures is primarily down to the effect of the elements in exposed aspects, or whether its growth form is heavily influenced by pest animals (which are certainly present in the area).

Another species that we were interested in seeing on Hoary Head is a rare native forget-me-not with blackish flowers and silver foliage, called Myosotis arnoldii, which is intriguingly found in only a few places in Marlborough (including Chalk Range) and on Hoary Head. On the day of our visit, the flowers of M. arnoldiiiĀ were on the cusp of opening, as can be seen below.

The other major destination on this weekend was the dolomite peak of Mt Burnett, which contains several species (and forms) that are endemic to this one mountain, including the relatively recently-described Myrsine argentea – a shrub (or sometimes, a small tree) with pale, highly reflective leaves. Like its relative, Myrsine divaricata, it can occupy some very unpromising places, where it can take on the kind of wind-sculpted form exhibited in the following image.

Many of the dolomite bluffs and outcrops of Mt Burnett have a craggy, shattered appearance, which lends them a dramatic character, as well as providing a wide range of niches for plants to occupy. A seemingly distinctive, compact form of mountain flax (Phormium cookianum) forms sheets over the steep rocky slopes, through which many shrubs emerge, including large numbers of Pimelea longifolia and impressive bushes of a particularly attractive Hebe, called H. townsonii.

Myrsine argentea (below, left) is also a common element of this shrubland, where its light, metallic colour contrasts against the surrounding foliage. Rock faces that are either too steep or smooth to support larger vegetation provide opportunities for a number of herbaceous species including a floriferous, yellow-flowered daisy called Senecio glaucophyllus, and an endemic member of the carrot family with attractive bronzish foliage and white flowers, Gingidia haematitica (which is shown below, right).

Wind is a persistent presence on Mt Burnett; a fact that is vividly impressed upon the vegetation, as in the case of the windshorn hummocks of Coprosma obconica (below, left) – a nationally rare species that is reasonably common amidst the flax and on exposed outcrops. A far less common inhabitant, the Mt Burnett form of the Melicytus obovatus complex (below, right), was of particular interest to me, due to the fact that we have planted many plants of this form in gardens, including within a recent Nelson project.

In a variety of habitats in upper parts of Mt Burnett, a species of ‘native iris’, Libertia mooreae, was in bloom. I was intrigued to see large swathes of this species growing on the top of a bluff in high light, where it contributes towards an interesting, somewhat spartan, ecological association in which Melicope simplex is particularly common.