An Unbroken Line

Urban sprawl threatens centuries-old plant species growing against the odds in one of Tāmaki Makaurau’s ancient lava fields.

An Unbroken Line

Urban sprawl threatens centuries-old plant species growing against the odds in one of Tāmaki Makaurau’s ancient lava fields.

A few weeks ago, I went with two old friends, landscape designer Philip Smith and photographer David Straight, to see what remains of the Southdown lava field, out the back of Penrose, overlooking the Manukau Harbour. We were there to inspect a strange, almost apocalyptic landscape, which features ancient fingers of lava, rare plants, as well as weeds, rubbish and abandoned supermarket trolleys.

It doesn’t look like much, but it’s incredibly important for both botany and geology in Tāmaki Makaurau. It’s also under threat from the East West Link, which would connect State Highways 1 and 20 by running along the edge of the Manukau Harbour, straight through the lava field: a 7km road projected to cost $1.85 billion.

The highway has a patchy history. It didn’t make it through a resource consent process in 2016, it was cancelled by the previous Labour Government and Mayor Phil Goff in 2017, and it’s been assessed as being one of the most expensive roads in the world per kilometre. In May, Forest & Bird won a Supreme Court judgment that sent the road back to the drafting board. Yet, under the proposed Fast-track Approvals Bill, and because it features on a list of supposed nationally significant roads established by the minister of transport, the lava field remains at risk. Smith tells us more.

What value do we place on the memory of a city? Within New Zealand architecture and landscape architecture, memory plays a major role in design narratives and in generating a sense of place. The irony is we often have less interest in (and conviction towards) cases where the memory of a city is still alive and kicking – where it comprises living organisms whose long-standing tenure on the land continues today in physical form.

One strange, largely forgotten urban fragment on the eastern margins of the Manukau Harbour is a fine example of this. Southdown is well-known among botanists in Tāmaki Makaurau Auckland, due to the remarkable fact that several species of regional and national significance have occupied this lava field in an unbroken line for centuries.

Having evaded the industrial development that steamrollered most of the nearby suburbs over the past hundred years, Southdown has recently found itself in the path of the resurrected Roads of National Significance plan, which aims to put a highway through the heart of it. The road has been widely criticised, and will establish an indelible barrier to the shoreline, affecting important populations of migratory seabirds.

As a friend of mine pointed out recently, matters such as this should be viewed in terms of ethics, not politics. After all, the collective values of a city should be born out of non-partisan, objective processes that develop over time periods much longer than election cycles.

Two of the species that endure at Southdown are native geraniums that Joseph Banks and Daniel Solander collected on their first days ashore, as part of Captain Cook’s voyages to New Zealand in 1769 and 1770. These two herbs have an unusual adaptation to drought, whereby they form swollen taproots that store energy; such that they can re-emerge from habitats like the cracks within lava fields as the seasons oblige. The presence of this taproot is undoubtedly the reason these species are known as matua-kūmara in Māori tradition.

One of them, Geranium retrorsum, is classified as Nationally Vulnerable in our national threat rankings, while the other, Geranium solanderi, is classified as At Risk. Both are of high regional significance, and both are fascinating survivors of a lava-field flora that Auckland (a city built over lava flows) should not simply ignore. Furthermore, both are worthy of cultivation within naturalistic gardens on account of their dissected foliage and small pink flowers.


Another strand of this site’s significance pertains to its place in this country’s natural sciences – specifically botany. More than 180 years ago, the missionary William Colenso walked through this part of Auckland on one of his epic journeys around the North Island. As he moved through what has become a tiny fragment of the lava fields of Ōtāhuhu, he described a new species (in the context of modern botany) called Coprosma crassifolia. Despite generations of encroachment by industrial facilities (including the now-defunct Southdown abattoir), this small-leaved shrub still grows in this place.

Colenso’s description of his visit goes some way towards explaining the resilience of the native species that have endured here: a landscape in which “scoria abounds; the ground being in some places as if entirely composed of it, in massy flat and continuous layers”. Further observations about the terracing of this stark volcanic landscape allude to the way in which Māori moulded landforms and geological features of Tāmaki Makaurau. Only the toughest plants survived in this place, and were therefore less readily displaced than members of our native flora in more agreeable habitats.

Following decades of neglect (during which weeds have become increasingly prevalent in its driest zones), Southdown can’t be described as a particularly scenic reserve – a circumstance almost certainly tied to its geography, standing as it does on the fringes of industrial Ōtāhuhu. That said, it exhibits the kind of wild character that landscapes develop when left to their own devices, and the dark blocks of lava that descend to the shoreline have a raw beauty (especially in contrast with the tawny, flame-shaped tussocks of Austrostipa stipoides that emerge from their cracks).

Public use of the area is primarily confined to an adjoining pathway for bikes and occasional walkers. One possible future for this site (and the remainder of the harbour edge linking Onehunga and Ōtāhuhu) would be to enhance its appeal to pedestrians and cyclists – akin to recent projects in Auckland, such as the Westhaven walkway.

Sitting as it does in the midst of other largely pragmatic suburbs, the dismantling of Southdown could be a relatively noiseless affair. Thankfully, a recent Stuff article by Erin Johnson brought details of the protracted battle over this roading project to the surface, highlighting determined legal resistance from Forest & Bird and local iwi. However, if the alarming Fast-track Approvals Bill is allowed to pass unopposed, the plants, animals and cultural values of places like Southdown will become vulnerable to being swept aside by an undemocratic, unilateral process.

We need to ask ourselves whether this is the kind of country we wish to live in and leave for future generations. One that extinguishes the pulse of those rare places where the underlying natural environment still remains, or a city in which the few lava fields, urban streams and forest fragments that have survived amidst urban sprawl continue to remind us of the many layers that define this place.

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