Aotearoa has a rich diversity of native angiosperms and gymnosperms. These are the two main taxonomy divisions of trees and plants. In this journal article we explore the range of species that fall within these two categories.
Angiosperms or flowering plants are the largest and most diverse group of plants in the world. Native angiosperms include kōwhai (fabaceae or legume fmaily), pōhutukawa, rātā, mānuka (myrtaceae or myrtle family), nikau (arecaceae or palm family), southern beeches (nothofagaceae or southern beech family), kawakawa (piperaeae or pepper family).
- Kōwhai is the unoffcial national flower of New Zealand. Kōwhai has bell-shaped yellow flowers.
- Pōhutukawa, the New Zealand Christmas tree, blooms with red flowers in summer. Rātā also produces a haze of red flowers.
- Mānuka has small white flowers. Beech trees produce tiny flowers. Large stands of beech forest grow in mountainous areas. Approximately 4.2 million hectares of New Zealand contains some beech and 2 million hectares is almost pure beech forest.
- Kawakawa flowers are produced on greenish, erect spikes 2.5-7.5cm long. After pollination the flowers gradually swell and become fleshy to form small, berry-like fruits that are yellow to bright orange.
- We also have grasses, such as tussock, flax (harakeke) and bulrushes (raupō), as well as maize.
Gymnosperms, or plants that produce a seed not contained within an ovary or fruit, include tōtara, kauri, mataī, rimu, and kahikatea.
- Kahikatea is the tallest tree in the New Zealand forest, with many specimens attaining a height of 60 metres.
- Kauri is recognized for its tall, straight trunk, which was fashioned into war canoes and used to build houses. The fourth largest tree in the world is a giant kauri called Tāne Mahuta in Waipoua Forest. Kauri belongs to the araucaria family.
- Tōtara has a bark that peels off in strips and a reddish-brown light timber. It is common in lowland areas of the North and South islands on fertile, well-drained to drought-prone soils.
- Mataī trees are recognized from the trunk’s hammered appearance, which is the result of chunks of bark flaking off.
- Rimu has characteristic long, drooping branches.
These gymnosperms are conifers (cone-bearing plants), the largest group of gymnosperms (the others are cycads, ginkgo.) A nickname for these trees is rakau rangatira as they are the tallest trees in New Zealand, often rising above the canopy of their surrounding trees. They are characterized by their cones which are the reproductive parts of the plant, and their needle-shaped leaves, in contrast with the variety of shapes of hardwoods’ leaves. They are softwoods, which makes them useful timber and slow-burning firewood. They have an ancient heritage in New Zealand. Not only do many live for centuries, but they are part of our earliest vegetation.
Species of the two main families of fern, cyatheaceae and dicksonia, grow in New Zealand. Cyathea ferns are scaly, while dicksonia ferns are hairy.
- Ponga (Cyathea dealbata) or silver fern is a national symbol.
- Mamaku (Cyathea medullaris) or black tree fern is the largest tree fern. It grows up to 20 metres tall.
- Wheki (Dicksonia squarrosa) or rough tree fern is a hairy tree fern.
Ferns produce pinnate (like pinnae, bird feathers) leaves, also called fronds, which usually unfurl from a fiddlehead. Unlike both angiosperms and gymnosperms, ferns reproduce using a spore, not a seed. Also, though we call them tree ferns, tree ferns are not trees as they are not woody and have no secondary growth (lateral growth of a trunk). Ferns existed on earth long before the flowering or cone-bearing plants evolved and are associated with the Carboniferous era.
Mosses, hornworts and liverworts
Mosses, hornworts and liverworts (bryophytes) are abundant in New Zealand and grow beside streams, on tree trunks and on the forest floor. They are an important part of carbon and water cycles. They reproduce via spores carried by water.
New Zealand has a wide array of ecological environments, some of which are surviving better than others.
Types of vegetation that stand out in New Zealand include kauri forest, podocarp forest, beech forest, tussock grasslands, coastal forest and alpine flora.
New Zealand species originated on Gondwana but developed in isolation over millions of years. Two waves of extinction occurred, the first with the Māori arrival and the second with the European arrival.
Historically, New Zealand was vegetated with ferns, podocarps and Araucarian pines.Today, beech forest is surviving better than most other forms of native vegetation due to its mountainous habitat. 2 million hectares of pure beech forest remains of 6.4 million hectares of native forest, and 4 million hectares of forest with some beech in them.
Planting natives is one way Aotea looks after our papakāinga.
What factors do we have to consider when planting natives?
We remember to consider the heights the plants will grow to in adulthood. We remember that plants that have a high canopy can protect smaller species from wind and frost. Aftercare for the ground is important; it may be necessary to weed, protect nutrition in the form of mulch, and moist soils are key. We try to keep the plants cool and moist. We aerate the soil.