Ackama

Adventures are important in life; they keep us young. I reflected upon this point as I headed into the hills above the Hokianga area, in search of rare plants that I’d never seen in the wild – foremost amongst which was turoa onamata (Ackama nubicola). Walking beside me were two men who are exemplary case studies for the statement above; Terry Hatch, one of the youngest 70-year olds you’re ever likely to encounter, and the not-quite-so-‘venerable’ Guy Bowden, a plantsman whose enthusiasm for the flora of Northland (and its conservation) is seemingly boundless.

Our destination on this occasion was a series of knobs and ridgelines in the Waima Range, that includes the highest point on Northland’s mainland. Turoa onamata endures on one of these ridgelines, where it grows in association with its close relative, makamaka (Ackama rosifolia). The fact that both species grow in close association came as a surprise to me, as I had assumed that they had embarked upon different evolutionary paths (and maintained their differences) due to isolation from each other.

Yet here they were, growing cheek-by-jowl on the same ridgeline. Aside from any other barriers, they may avoid hybridisation by the fact that these species flower at separate times; A. rosifolia in spring and early summer (its flowers are pictured below, in bloom during the last days of November), and A. nubicola in late summer.

An interesting aspect of the area in which turoa onamata endures is that this is not a pristine remnant of a bygone ecology. To the contrary, it has obviously been cut over, burned and grazed for much of its recent history. This makes a good deal of sense when one considers Ackama rosifolia‘s association with disturbed habitats (such as areas where logging has taken place)¹. Before human disturbance became a factor in the landscape, species such as these would have found their opportunities in open places like cliffs, streamsides or slip faces.

Ackama is one of the few native genera to have a name derived from Te Reo Māori². It was described by an early botanist, Allan Cunningham, who adapted the scientific name from its Māori name, makamaka (although Cheeseman rightly identified it as a “not very successful anagram”³). It is a small genus of four species; two from New Zealand, and two that are found in Australia⁴.

Upon first viewing this extremely rare species in its natural habitat, I was struck by the similarities between A. nubicola and its distant South African cousin, Cunonia capensis. Not only do the buttery stipules (that enfold the new leaves) bear a remarkable resemblance to those of Cunonia capensis⁵; the scene in which turoa onamata occurred was reminiscent of the ravine on Table Mountain (in South Africa) where I had viewed C. capensis several years beforehand.

Both Table Mountain and the Waima Range are subject to unusual weather effects, whereby cloud rolls in off the sea and enshrouds each of them (effectively making them like ecological islands within their respective locations). In the case of the Waima Range, this has led to the development of a distinctive cloud forest, in which a range of endemic plants and animals have evolved⁶.

This is alluded to in the specific epithet, ‘nubicola‘ – which means “cloud-dwelling”. In addition to A. nubicola, two other major plant discoveries have been made in this cloud forest since the beginning of the 1980s – an attractive, large-leaved tree daisy (Olearia crebra), and a shrubby Coprosma that bears the name of its geographical home (C. waima).

When describing how a plant differs from other species in the flora, botanists often refer to diagnostic features that are barely discernible to most other people, right down to the level of the hairs on a leaf. However, A. nubicola‘s most obvious distinguishing characteristic is blatantly clear for all to see – the rather beautiful stipules mark this out as a singular species, even from a distance (as shown in the photos below). In addition to the stipules, the leaves of A. nubicola are much larger than A. rosifolia. To my eyes, they are somewhat reminiscent of the leaves of the Three Kings Islands titoki (Alectryon excelsus ssp. grandis), in terms of the arrangement of the leaflets and the way in which they sit upon the canopy⁷.

The ridge on which we observed this small tree is very much a tale of two sides; with turoa onamata only occupying the colder, exposed, south-facing (seaward) slope. On the opposite north-facing side, large specimens of makamaka were a conspicuous element of the vegetation, which looked considerably more lush (no doubt due to a measure of protection from the prevailing winds)⁸.

A. nubicola emerged from large swathes of Blechnum novae-zelandiae, as well as growing in association with other small trees in the stunted, windshorn forest and scrub. The constant conditions that it endures within nature help to explain why it is a challenging candidate for cultivation. Almost unrelenting winds provide continual air movement, whilst the regular cloud cover delivers consistent levels of moisture. It is therefore unsurprising that it is intolerant of both humidity and drought⁹ within cultivation.

Attempts to cultivate A. nubicola have been limited to a relatively small number of plants, that have been grown for cultural or scientific purposes. Following its discovery, Guy Bowden was asked to grow this species (on behalf of DoC and iwi), which he maintained with great success at his coastal nursery for many years (before giving the plants to the Department)¹⁰. Due to its critically endangered status, it is unlikely to figure on the radar of horticulturists for some time.

Despite this, its story is worth sharing – as an example that exciting discoveries are still out there to be made in the majestic and varied landscapes that make up our country. One final note on A. nubicola regards its evocative Māori name, turoa onamata – which was obviously conferred following its discovery (in 2000), and means “long standing from the beginning of time”¹¹. This represents an interesting perspective on this “new” species; one that places it as an entity that belongs to this place, rather than a curious novelty (as it may be interpreted within science).

The frothy white flowers and plum-tinted foliage of this Northland endemic make it an attractive small tree for the garden, as well as a magnificent sight (when in full stride) within nature. Furthermore, its appeal is extended by the reddish-pink fruits that adorn the tree towards the latter end of summer.

It is interesting to read the comparisons that are sometimes made between different plants (especially for gardeners who are not particularly familiar with the New Zealand flora). In the case of makamaka, Thomas Kirk noted “the foliage bears some resemblance to that of the rowan or mountain-ash (Sorbus aucuparia) of Europe, but is more graceful and of a lighter green”¹².

Despite the praise of many authors, A. rosifolia has not become a common sight in New Zealand gardens. It is a reasonably easy tree to grow, on the condition that it is given a position where it does not dry out too much.

Accordingly, the rule that applies for many bush edge species is a useful guide for placing makamaka in the garden – “roots in the shade, head in the sun”. Another comment that I would make regarding its cultivation is that it should be allowed room to achieve its natural spreading form (around 3 to 4m), as it can be tricky to maintain an elegant appearance when pruning its lateral branches¹³.

Makamaka is naturally found from near Kaitaia to just north of Wellsford⁹. Despite its restriction to the Northland region, it will grow at least as far south as Wellington. It was discovered to science by the early botanist Allan Cunnngham in 1826, at Hokianga.