Podocarpus

Certain trees are venerated within various cultures; sometimes for the character of the trees themselves, and sometimes for the value of their timber. The tōtara (Podocarpus totara) is one such species. Although modern New Zealanders frequently talk of kauri in more hallowed terms, the tōtara is the most sacred tree within Māori tradition. Apart from the durability and workability of the timber, its reputation was ensured by the fact that tōtara grows throughout the country (as opposed to kauri, which is only found in the north), and the fact that this was the timber from which Māori created their great taua (war canoes).

In New Zealand’s early colonial period, European settlers also developed a high regard for the tōtara as a building material – on account of its durability, and the ease by which it could be fashioned into fence posts. As a result, it has become an important part of our rural heritage.

New Zealand has four species of tōtara that, collectively, occupy a wide range of ecologies from the coast to the mountains. Podocarpus is a relatively large genus, that occurs throughout the Southern Hemisphere, and further north into parts of Asia.

The name is derived from the Greek for foot (podos) and fruit (karpos), and refers to the fleshy stalk (foot) on which the seed sits. Although commonly known to botanists, it is worth mentioning that tōtara (like kauri, rimu and many other well-known native trees) is a conifer. This is a connection that is easy to miss, as it does not look similar to typical Northern Hemisphere conifers, like pines and cedars.

It is relatively unsurprising that this species was not recognised as distinct until the 1880s. Quite apart from the fact that tōtara (Podocarpus totara) somehow escaped the attention of botanists up to the 1820s, Podocarpus laetus and tōtara are so physically similar that they could easily register as simply varied forms of the same species.

One of the primary ways of distinguishing P. laetus is alluded to in the common name, thin-barked tōtara. Whilst P. totara generally has thick, cork-like bark, thin-barked tōtara normally has papery bark. Another distinction is that thin-barked tōtara has longer, broader leaves that culminate in a pungent leaf tip¹. These characters are, however, somewhat variable, and the proper way of identifying P. laetus is by observing its leaf buds – which are swollen to the extent that they are wider than the branchlets on which they grow.

P. laetus is also known by the name of mountain tōtara, due to the fact that it is more prevalent in higher altitude areas (although it occurs at all altitudes in New Zealand). Although I have included this common name here, it is not an ideal title, as it risks confusing this species with the creeping Podocarpus nivalis (snow tōtara), which is known by the same title.

The ability of Podocarpus laetus to endure extreme montane climates is evidenced by its occurrence in the area shown within the photos above and below. This regenerating forest on the eastern shores of Lake Ohau (standing at the base of Ben Ohau) represents a remnant of some of New Zealand’s driest forests. In this association, thin-barked totara emerges from fairly typical subalpine scrub (such as matagouri, Discaria toumatou, and Coprosma propinqua), which also supports emergent specimens of kowhai (Sophora microphylla) and broadleaf (Griselinia littoralis).

Thin-barked tōtara generally attains smaller dimensions than Podocarpus totara, and is therefore useful in situations where a smaller tree is desired. As a plant that favours high-altitude zones, it should be utilised more in montane and subalpine areas – especially in dry regions (like the Mackenzie Basin or Marlborough), where it would have been a prominent part of the vegetation prior to human settlement (as demonstrated by the forest pictured below, growing on the extremely steep slopes of Chalk Range).

As with P. totara, thin-barked tōtara is a useful species for hedging, an application in which we have planted it before (at Lake Karapiro). Tōtara hedges are, in fact, a feature of New Zealand’s rural landscapes; and have become much more frequently planted within landscape architecture.

In 2015, this nomenclaturally-challenged tree was subjected to another name change, having passed through a long period of being known as Podocarpus hallii, and a brief period in which P. cunninghamii was accepted as the legitimate name. In this matter, the plants are (as always) completely indifferent to their altered status.

The ability of plants to adapt to different living stations is well demonstrated by the example of the snow tōtara. Whilst all of its close relatives are upright trees exceeding 4m in height (and becoming forest giants in the case of P. totara), Podocarpus nivalis commonly grows as a creeping mat, in the exposed montane areas that it inhabits.

Snow totara is also able to grow to slightly taller dimensions (reaching around 1m high), but it is mostly seen within cultivation in a creeping state. Although slow, this is one of the most useful plants for establishing ground coverage on harsh, exposed sites in cold areas of New Zealand (even within the inhospitable climate of the Mackenzie Basin). This is unsurpising, as P. nivalis is perfectly capable of colonising scree slopes and other extreme habitats.

The compact growth form of P. nivalis brings increased attention to a feature that is universal to all New Zealand Podocarpus – the bright red fruits² that are, for obvious reasons, less apparent on its taller cousins. Another seasonal characteristic of snow totara is the colour that the foliage takes on under extremely cold conditions; when it transforms from the typical dull green of tōtara to an attractive burnished bronze hue.

Podocarpus nivalis grows best in a sunny aspect and well-drained conditions, and exhibits considerable drought tolerance from an early stage of its development. It is found naturally from the Waikato southwards, mostly in habitats that are rendered open (or semi-open) by extreme climatic conditions. Based on this, it is therefore surprising that P. nivalis is amenable to cultivation in many lowland sites and even in the warm, humid north (where montane species often struggle, for obvious reasons).