Libocedrus

The whole business of ‘false cedars’ is a bit odd. I’m not sure that I’m sufficiently interested to get to the bottom of it, but one look at the patently different foliage of true cedars (members of the genus Cedrus) begs the question of why a couple of cypresses are masquerading as cedars within New Zealand botany.

The answer partially lies in the practical usage of trees and the qualities of their timbers. This is evident in the old-fashioned application of ‘pine’ with reference to our podocarps (notably by settlers) – red pine for rimu; brown pine for miro, black pine for matai, and white pine for kahikatea, amongst other examples.

Whilst reference to podocarps as ‘pines’ now sounds distinctly old-fashioned, Libocedrus (and its relatives from the genera Calocedrus, Papuacedrus and Austrocedrus) are comparatively stuck with their taxonomic association with cedars. As is always the case, plants themselves have no comment to make on the matter of names, and will continue going about their business as they always have.

As the only members of the cypress family native to New Zealand, I have always felt that our two native species of Libocedrus, L. plumosa and L. bidwillii, seem slightly out of place in many of the landscapes to which they naturally belong. This is especially true for kawaka (Libocedrus plumosa) in northern habitats such as ridgelines in kauri forest.

Like our native beeches, Libocedrus is a textbook genus for getting biogeographers excited about Southern Hemisphere distribution, with 2 species present in New Zealand, 3 within New Caledonia, and a sole species in Chile.

In his seminal 1889 work, ‘The Forest Flora of New Zealand’¹, Thomas Kirk fittingly described kawaka as a ‘noble’ species – due in large part to Libocedrus plumosa‘s upright, conical growth form and straight, clear trunk. With trees, good posture clearly counts for something.

The image below shows the way in which Libocedrus frequently registers on ridgelines and in hill country – emerging from regenerating forest (in this case with rimu and kahikatea). The vibrant, light green hue of kawaka’s fern-like foliage establishes a vivid contrast with the relatively muted greens of many of its associates; providing a good example of how observation of natural plant communities can inform design.

In her pioneering writing about the cultivation of native plants (from the early 1970s), Muriel Fisher shared Kirk’s sentiments about our ‘noble’ kawaka, whilst expressing consternation at the widespread planting of inferior exotic cypresses when our native species was practically unknown. Fifty years later, Libocedrus plumosa is still under-utilised within landscape architecture, but it is gradually becoming more visible within street tree plantings, parks and gardens.

Within the most important publication in recent years on our native trees², John Dawson recorded valuable information about kawaka’s ecological preferences – noting the importance of disturbance (without which L. plumosa disappears from mature forest). This goes some way to explaining its relative scarcity in our forests.

In line with this, kawaka should be planted in an open aspect, or where it can emerge through a relatively low canopy in light shade. In warmer parts of the country, some relief from the most intense afternoon sun is also ideal for establishment.

This predominantly northern species has an interesting, disjunct distribution, occurring in the top half of the North Island (from Te Paki to western Waikato and Gisborne) and then reappearing in Golden Bay (at the top of the South Island). Libocedrus plumosa is one of many species encountered by the Cunninghamii brothers (in this case, Richard Cunningham at Bay of Islands) on their pioneering botanical journeys in the north of New Zealand during the 1830s.