Kāmahi

Description
Kāmahi (Pterophylla racemosa, formerly Weinmannia racemosa) is a widespread evergreen native tree that typically grows 15–25 metres tall. It has small, leathery leaves with distinctly toothed margins, arranged in opposite pairs along the branches. During spring and summer, kāmahi produces masses of small white to cream flowers arranged on upright racemes, often giving flowering trees a pale, fluffy appearance. These are followed by small dry capsules containing numerous tiny seeds that are dispersed by wind. Kāmahi can grow as a conventional tree from the ground but can also begin life as an epiphyte on tree-fern trunks or other trees before eventually developing its own root system.

Habitat
Kāmahi is endemic to New Zealand and is widespread across the North Island, South Island and Rakiura/Stewart Island. It occurs from lowland forests into montane environments and is particularly abundant in cool, moist, high-rainfall regions. Kāmahi grows on hillsides, ridges, forest margins and disturbed sites and is especially prominent in many forests of the western South Island. It tolerates relatively infertile and acidic soils and can become a dominant canopy or subcanopy tree. Its ability to establish following disturbance also makes it an important component of regenerating native forest.

Cultural Importance
Kāmahi has a history of use in both mātauranga Māori and early European settlement. Its bark is rich in tannins and was used in traditional preparations and for producing dyes. The timber is strong and hard and has been used for construction, flooring and other practical purposes. Kāmahi is also valued today as a major component of indigenous forests and as a significant nectar-producing tree, with its flowers contributing to distinctive kāmahi honey.

Ecological Role
Kāmahi is an important canopy and subcanopy species and can dominate large areas of native forest. Its abundant flowers produce nectar and pollen that support native insects and nectar-feeding birds. The foliage and branching structure provide habitat for insects, while mature trunks can support mosses, lichens, ferns and other epiphytes. Kāmahi is also important in forest succession because it can establish readily in disturbed areas and beneath suitable vegetation, helping rebuild forest structure following slips, storms or other disturbance.

Associated Birds

Tūī: Tūī visit flowering kāmahi to feed on nectar, particularly when large numbers of trees flower simultaneously. While moving between the numerous small blossoms, tūī can transfer pollen and contribute to pollination. They also forage among kāmahi foliage and branches for insects.

Korimako/Bellbird: Korimako feed extensively on nectar and make use of flowering kāmahi as a seasonal food source. Large flowering trees can provide substantial quantities of nectar across the forest canopy. As korimako move between flowers and trees, they can also assist with pollen transfer.

Kākā: Kākā use mature native forests containing kāmahi for feeding and shelter. Their varied diet includes nectar and invertebrates, allowing them to make use of flowering trees and insects found around trunks, branches and decaying wood. Large kāmahi also contribute to the mature forest structure required by kākā.

Tauhou/Silvereye: Tauhou feed on nectar and insects and can forage extensively around flowering kāmahi. The numerous small flowers provide seasonal feeding opportunities, while the dense foliage supports small invertebrates that tauhou search for among leaves and branches.

Riroriro/Grey Warbler: Riroriro forage through kāmahi foliage for insects, spiders and other small invertebrates. The dense branching and evergreen leaves provide extensive feeding and sheltering habitat, particularly where kāmahi forms an important component of the forest canopy and subcanopy.

Conservation Status
Kāmahi is classified as Not Threatened in New Zealand and remains one of the country's most widespread native forest trees. It can be locally abundant and sometimes dominates extensive areas of forest. However, kāmahi is highly palatable to introduced brushtail possums, and sustained browsing can cause severe canopy damage or the death of mature trees. Maintaining effective possum control is therefore particularly important in forests where kāmahi is heavily browsed.

Interesting Facts

• Kāmahi is endemic to New Zealand, meaning it occurs naturally nowhere else in the world.
• It is one of the most widespread native forest trees in the country.
• Kāmahi was long known scientifically as Weinmannia racemosa but is now classified as Pterophylla racemosa.
• It can sometimes begin life growing on a tree fern or another tree before developing roots that reach the ground.
• Its masses of small cream-white flowers can make entire sections of forest canopy appear pale during flowering.
• Kāmahi flowers are an important nectar source for insects and birds and are also used by honey bees to produce kāmahi honey.
• The species can tolerate relatively nutrient-poor and acidic soils.
• Kāmahi is an important forest regeneration species and can establish readily following natural disturbance.
• Introduced possums can heavily browse kāmahi foliage and cause serious damage to mature trees.

Conservation Tips
Controlling introduced possums is particularly important for maintaining healthy kāmahi forest, as repeated browsing can severely damage mature trees. Protecting regenerating native vegetation allows kāmahi seedlings to establish naturally following disturbance. In restoration projects, kāmahi is particularly useful in cool, moist environments and can contribute to the development of a permanent native canopy. Maintaining a diverse mixture of locally appropriate trees, shrubs and tree ferns alongside kāmahi will create more complex habitat and provide a wider range of food resources for native wildlife.

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