Plants make an impression on us on the basis of various qualities – such as flower or leaf colour/shape, their overall form, or even the way in which they move in the wind. In the case of kanuka (Kunzea spp.), the tree’s character is established to a large degree by the attractive branching structure that it frequently exhibits. When viewed within a woodland setting, the branching structure of kanuka trees often joins up to create a beautiful silhouetted network, with a ‘graphic’ quality to them.
Another desirable feature of kanuka is the profusion of white flowers that trees produce in mid-summer. In addition to their aesthetic appeal, these play an important ecological role in the mass supply of nectar and pollen for a range of animals, such as native bees and geckos. Furthermore, it is not just kanuka’s flowers that perform an ecological function. The bark is valuable habitat for a variety of native insects, which are duly preyed upon by insectivorous birds, whilst the leaves are a favoured food of our common stick insect.
Confusion has surrounded the taxonomy of kanuka for a long time. Until 1983, it was classified as a member of the genus to which manuka belongs, Leptospermum – an understandable assumption, considering the similarities between manuka and kanuka. Following its transfer to Kunzea, two species were officially recognised as occurring within New Zealand; the widespread and variable K. ericoides, and a Great Barrier Island endemic, K. sinclairii. However, in late 2014, Peter de Lange (a leading conservation scientist), has completed a revision of Kunzea in New Zealand, in which several new species have been recognised (including Kunzea amathicola, a species particularly associated with sand habitats, which is pictured below).
It is worth noting, out of interest, that both kanuka and manuka are members of the same family as pohutukawa and rata (the myrtle family). Another useful point to include herein is the difference between manuka and kanuka; a matter that people often ask about. In simple terms, one good (but not foolproof) way of distinguishing the two (when they are not in flower) is that kanuka foliage is normally soft to the touch, whilst manuka’s foliage is comparatively harsh. Another distinction is that the flowers of kanuka are generally clustered in groups and appear later in the year (in summer), whilst manuka’s flowers are borne singly upon the branches.
Kunzea is named in honour of a nineteenth-century German natural sciences professor, Gustav Kunze.
The Auckland Harbour Bridge is an unlikely place to find a remnant population of a threatened plant, and it seems doubly strange that it should be a variety of the apparently ubiquitous kanuka. However, the steep banks adjacent to the Bridge’s northern end are graced by this distinctive, and increasingly rare, species of kanuka, Kunzea linearis (as shown in the photo below, in which the narrow-leaved kanuka can be seen in the upper right quarter).
This represents one of the most southerly occurrences of this Far North-centred variety, and it has been suggested that these outlier populations may be unnatural – having originated from the inadvertent or deliberate introduction of material by Māori, and possibly early European settlers1.
Kunzea linearis is a particularly attractive species for cultivation, as its narrow leaves give it a soft appearance. It is a comparatively compact form of kanuka, which grows up to 8m (other New Zealand kanuka can reach up to 30m tall). In the garden, it may be utilised for the scale that it can provide, whilst maintaining a narrow growth habit and allowing light penetration. It is also valuable for the beauty of its branching structure, which looks especially striking in combination with modernist architecture.
It is primarily found in coastal areas, where it occupies cliffs and shrubland. Bearing this in mind, it should be provided with reasonably well-drained conditions within the garden. As mentioned above, K. linearis is a threatened species, with the threat ranking of ‘Declining’. Two related problems that it faces are coastal development and the assumption that kanuka is ubiquitous (and therefore dispensable and not requiring protection).
It was first recognised as a distinct form by Thomas Kirk, who collected the plant from a pā site adjacent to the Waitemata Harbour in the 1860s. Kirk stated that it should probably be viewed as a distinct species2, an observation that has received official recognition in Peter de Lange’s 2014 revision of the genus.