Conifers are cone-bearing, woody seed plants. They belong to an ancient group called gymnosperms, which appeared 360 million years ago – long before flowering plants. In most temperate and tropical forests conifers have been superseded by flowering plants, but in New Zealand they dominate rainforests and some shrublands with infertile soils.
Conifers in New Zealand
New Zealand’s 20 native conifers are found nowhere else. They belong to four families:
- the araucarian family, Araucariaceae – New Zealand’s sole member is kauri (Agathis australis)
- the celery pine family, Phyllocladaceae – with three species in New Zealand
- the cypress family, Cupressaceae – with two species in New Zealand
- the podocarp family, Podocarpaceae – the largest conifer family in New Zealand, with seven genera and 14 species.
Conifers reproduce by means of male and female cones. Male cones produce pollen, and female cones produce seeds. In some New Zealand conifers, male and female cones grow on separate trees. Unlike the seeds of flowering plants, conifer seeds are not enclosed in a fruit but are attached to a cone scale.
Kauri, kaikawaka and kawaka are the only native conifers to produce woody cones that split open when mature, releasing seeds into the wind. The seed cones of podocarps and celery pines are smaller, surrounded by a fleshy support or cover, and their seeds are distributed by birds.
All the native conifers are evergreen. They have narrow, needle-like or scale-like leaves, and in this respect contrast with many flowering trees, which are broad-leaved. The juvenile leaves of some are quite different from their adult form.
Foresters often call conifers softwoods, and flowering trees hardwoods. These terms are not an absolute guide to the hardness of their wood, but generally most flowering trees have harder wood than conifers. Whau (Entelea arborescens) is one exception – its wood is so soft and light that it was used by Māori for floats on their fishing nets.
There is debate as to whether New Zealand’s conifers are direct descendants of plants that grew on the supercontinent Gondwana, over 85 million years ago, or are more recent arrivals from Australia and New Caledonia. New Zealand has conifer fossils from Cretaceous times (63–80 million years ago), including a type of kauri and some podocarps, but they are not identical to today’s conifers. Other gymnosperm fossils (ginkgo, cycad and gnetale) have been found in Cretaceous deposits, but these plants died out in New Zealand millions of years ago.