Kohekohe
Didymocheton spectabilis
This native plant, known as Kohekohe (scientific name: Didymocheton spectabilis , synonym Didymocheton spectabilis ), is a remarkable species endemic to New Zealand. It is characterized by its unique features, ecological role, and cultural significance. This comprehensive guide provides detailed information on its care, propagation, and importance within the New Zealand ecosystem. Understanding this plant contributes to the appreciation of our rich biodiversity and heritage, and supports conservation efforts for native trees .
Plant Description
Didymocheton spectabilis is a spectacular medium-sized tree that typically grows 10-15 meters tall, occasionally reaching 20 meters in optimal conditions. The tree is renowned for its beautiful glossy, dark green pinnate leaves that can reach 40 cm in length, composed of 4-8 pairs of leaflets plus a terminal leaflet. Each leaflet is 5-15 cm long, with a distinctive asymmetric base and smooth margins. The most remarkable feature is its cauliflorous flowering habit - waxy white flowers emerge directly from the trunk and main branches in spectacular sprays during winter (May to August). These are followed by green capsules that ripen to reveal bright orange-red fruits containing glossy black seeds. The bark is pale grey-brown and relatively smooth on younger trees, becoming slightly rougher with age. The tree has a spreading canopy that provides excellent shade.
Quick Facts
| Scientific Name | Didymocheton spectabilis |
|---|---|
| Height | 10-15 meters (occasionally to 20m) |
| Spread | 5-10 meters |
| Water Needs | Moderate to high - Prefers consistent moisture |
| Light | Partial shade to full sun (when mature) |
| Frost Tolerance | Tender - Requires frost-free conditions |
| Salt Tolerance | Moderate - Tolerates coastal conditions with protection |
| Growth Rate | Moderate to fast in good conditions |
| Lifespan | 100+ years |
Climate Best Suited to
Kohekohe thrives in warm temperate to subtropical climates with high humidity and minimal frost. It is naturally found in coastal and lowland forests of the North Island and northern South Island. This tree requires protection from cold winds and frost, particularly when young. It performs best in areas with warm, humid summers and mild winters, typical of northern New Zealand coastal regions.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | Excellent |
| Wellington | Good - Provide shelter from wind |
| Christchurch | Poor - Too cold and dry |
| Dunedin | Poor - Too cold |
| Hamilton | Good - Protect from frost when young |
| Tauranga | Excellent |
| Nelson | Moderate - Choose warm, sheltered sites |
| Napier | Good - Provide summer water |
| Palmerston North | Moderate - Protect from frost |
| Invercargill | Poor - Too cold |
Plant Habitat
In its natural habitat, Didymocheton spectabilis is found in coastal to lowland forests throughout the North Island and in the Marlborough Sounds and Nelson areas of the South Island. It typically grows from sea level to about 600 meters elevation, preferring warm, humid, sheltered valleys and coastal forests. Kohekohe is often found growing with other coastal forest species such as puriri, karaka, and nikau palm, forming part of the diverse canopy and subcanopy layers. It thrives in deep, fertile soils with good moisture retention and high organic content. The species is particularly abundant in areas protected from strong winds and salt spray, though it can tolerate some coastal exposure when sheltered by other vegetation. Young trees typically establish in the shade of the forest canopy, gradually growing toward the light.
Growing Requirements
Soil Requirements
Kohekohe prefers deep, fertile, well-drained soils with high organic content, similar to forest conditions.
- Rich, humus-laden soil ideal
- Good drainage essential
- Slightly acidic to neutral pH
- Benefits from leaf litter mulch
Light Requirements
Young trees prefer shade, gradually tolerating more sun as they mature and establish.
- Shade essential when young
- Gradually increase sun exposure
- Mature trees tolerate full sun
- Dappled shade ideal throughout life
Water Requirements
Consistent moisture is important for healthy growth, particularly during establishment and dry periods.
- Regular water during establishment
- Maintain consistent soil moisture
- Drought sensitive when young
- Mulch to retain moisture
Planting and Establishing
When planting Didymocheton spectabilis , choose a sheltered site protected from frost and strong winds. Young plants are particularly vulnerable and require shade for the first few years. Plant in spring after frost danger has passed. Prepare a large planting hole with plenty of compost and leaf mold to replicate forest soil conditions. Plant at the same depth as in the container, firm soil gently, and water thoroughly. Apply a thick layer of organic mulch, keeping it away from the trunk. Provide temporary shade using shade cloth or plant under existing tree canopy. Water regularly during the first two years, ensuring soil remains moist but not waterlogged. Protect from frost with frost cloth during the first few winters in marginal areas. Feed annually with slow-release fertilizer and maintain the mulch layer. As the tree establishes, gradually remove shade protection.
Ecological Role
Kohekohe plays a crucial ecological role in New Zealand's coastal and lowland forests. The spectacular winter flowers provide nectar for native birds, particularly tui and bellbirds, during a time when few other nectar sources are available. The bright fruits are eagerly consumed by kereru (wood pigeons) and other fruit-eating birds, which disperse the seeds. The dense canopy provides important habitat and shelter for various native birds and insects. Epiphytic plants, including native orchids and ferns, often establish on the trunk and branches of mature trees. The leaf litter contributes to forest floor ecology, supporting decomposer communities. As a canopy tree, it helps maintain forest humidity and provides shade for shade-tolerant understory species. The tree is also host to various native insects, including the spectacular puriri moth caterpillar in some regions.
Uses & Significance
Garden Uses
Kohekohe is valued as an ornamental tree for its attractive foliage, spectacular flowers, and shade-providing qualities.
- Specimen tree for large gardens
- Shade tree for subtropical gardens
- Forest restoration projects
- Bird-attracting gardens
- Coastal forest plantings
Ecological Value
This tree provides significant ecological benefits in garden and restoration settings.
- Winter nectar source for birds
- Fruit for native birds
- Habitat for epiphytes
- Shelter and nesting sites
- Forest canopy restoration
Landscaping Uses
In landscape design, Didymocheton spectabilis serves as an excellent specimen or shade tree for larger subtropical gardens. Its glossy foliage provides year-round appeal, while the winter flowering adds spectacular seasonal interest. Use it as a focal point where the unique trunk-borne flowers can be appreciated up close. In forest-style gardens, combine with other native trees like puriri, karaka, and nikau palms to create an authentic New Zealand coastal forest atmosphere. The tree works well in parks and large gardens where its ultimate size can be accommodated. It's particularly effective near outdoor living areas where its shade is valued in summer. Consider underplanting with native ferns and shade-loving groundcovers to complete the forest floor effect. In restoration projects, kohekohe is valuable for re-establishing canopy cover in degraded coastal forests.
Seasonal Care Calendar
Spring
New growth period with fresh foliage emerging.
- Apply slow-release fertilizer
- Refresh mulch layer
- Plant new specimens
- Check for pest issues
Summer
Active growth period requiring consistent moisture.
- Water during dry periods
- Monitor for drought stress
- Maintain mulch to conserve moisture
- Light pruning if needed
Autumn
Preparation for winter flowering season.
- Reduce watering slightly
- Prepare frost protection if needed
- Clear fallen leaves from paths
- Watch for flower bud formation
Winter
Spectacular flowering period on trunk and branches.
- Enjoy the unique flowers
- Protect from frost if necessary
- Observe bird visitors
- Minimal maintenance required
When to Prune and How Much
Kohekohe requires minimal pruning and is best left to develop its natural form. Any necessary pruning should be done in late spring or early summer after flowering and when the tree is actively growing.
- Remove dead or damaged branches anytime
- Prune for shape only when young
- Avoid heavy pruning which can stress the tree
- Remove lower branches gradually if needed for access
- Never top the tree as it ruins its natural form
When pruning is necessary, make clean cuts just outside the branch collar to promote proper healing. Large pruning wounds can be susceptible to fungal infection, so avoid removing large branches unless absolutely necessary. The tree naturally develops an attractive form without intervention.
How to Grow Kohekohe
Cultivating Kohekohe ( Didymocheton spectabilis ) is a rewarding endeavor for any gardener interested in New Zealand's unique flora. This species can be propagated through several methods, each requiring specific conditions to ensure healthy growth and establishment. Successful propagation depends on mimicking the plant's natural environment and providing consistent care during the early stages of development.
From Seed
Propagation from seed is often the most effective way to produce a large number of Kohekohe plants. Seeds should be collected when they are fully mature. Freshly collected seeds generally have higher germination rates than those that have been stored for long periods.
Seeds must be sown fresh as they lose viability quickly. Collect fruits when capsules split to reveal the orange-red aril surrounding black seeds.
- Remove the fleshy aril by washing in water
- Sow immediately in seed-raising mix
- Cover seeds lightly with mix
- Keep warm (20-25°C) and moist
- Germination occurs in 2-4 weeks
Seedlings require shade and consistent moisture. Transplant when 10-15 cm tall into individual pots.
From Cuttings
For those wishing to replicate specific characteristics of a parent plant, vegetative propagation via cuttings is the preferred method. This technique ensures that the new plants are genetically identical to the source. Semi-hardwood cuttings taken during the appropriate season usually yield the best results for this species.
Cuttings can be challenging but are possible with proper technique and timing.
- Take semi-hardwood cuttings in late summer
- Use 10-15 cm tip cuttings with 2-3 leaf pairs
- Remove lower leaves and dip in rooting hormone
- Insert in pumice or perlite mix
- Maintain high humidity and bottom heat
Additional Methods
Depending on the growth habit of Kohekohe, other methods such as air layering might also be viable options. Air layering is particularly suitable for plants with branches that are difficult to bend to ground level but can produce rooted sections while still attached to the parent plant.
Air layering can be successful on young branches and is useful for producing larger plants more quickly.
- Select a pencil-thick branch in spring
- Remove ring of bark 2-3 cm wide
- Apply rooting hormone to exposed area
- Wrap with moist sphagnum moss and plastic
- Roots develop in 3-6 months
Pests & Diseases
Didymocheton spectabilis is generally healthy but can be affected by several pests and diseases. Scale insects occasionally infest branches and leaves, particularly in humid conditions with poor air circulation - control with horticultural oil sprays. The puriri moth caterpillar may bore into the trunk, creating characteristic seven-shaped galleries, though this is part of the natural ecology and rarely fatal to healthy trees. Leaf-eating caterpillars can defoliate young trees in spring - monitor and hand-pick or use Bt spray if severe. Root rot can occur in poorly drained soils, so ensure good drainage at planting. Frost damage appears as blackened leaves and shoots - protect young trees in marginal areas. Aphids may attack new growth but are usually controlled by natural predators. Fungal leaf spots occasionally appear in very wet conditions but are generally not serious. Regular monitoring and maintaining tree health through proper cultural practices is the best defense.
Cultural Significance
Kohekohe holds cultural significance in Māori tradition, though it was not as extensively used as some other native trees. The tree was known and valued for specific purposes, and its presence was an indicator of fertile, quality land.
- Wood occasionally used for carving small items
- Leaves used in traditional medicine preparations
- Indicator of good soil and favorable growing conditions
- Flowering time used as a seasonal marker
- Part of the coastal forest ecosystem valued for resources
Bonus Tip
To fully appreciate the spectacular cauliflorous flowering of kohekohe, position garden lighting to illuminate the trunk during winter flowering. The white waxy flowers emerging directly from the bark create a magical effect when lit from below in the evening. For the best flowering display, ensure the tree receives adequate moisture during autumn as flower buds develop. The flowers are fragrant, particularly in the evening, so plant near outdoor living areas or windows where the scent can be enjoyed. Remember that young trees may take 10-15 years to begin flowering, but the wait is worthwhile for this unique display. Creating a forest-like environment with high humidity and organic mulch will help your kohekohe thrive and flower more prolifically.
Related Plants
Explore other native plants that share similar characteristics or habitats with Kohekohe ( Didymocheton spectabilis ), offering further insights into New Zealand's diverse flora. These related species provide context and opportunities for complementary planting in your garden.
Plant Conservation
Didymocheton spectabilis is currently listed as Not Threatened in New Zealand, with healthy populations in suitable habitat. However, like many coastal and lowland forest species, it has experienced significant habitat loss due to land clearance for agriculture and urban development. The species is also vulnerable to browsing by possums, which can severely damage or kill young trees. Conservation efforts focus on protecting remaining coastal forest remnants and including kohekohe in restoration plantings. The tree is increasingly valued in urban environments for its ornamental qualities, helping to maintain genetic diversity outside natural forests. Home gardeners can contribute to conservation by growing this species, particularly in northern regions where it thrives. When establishing kohekohe, source plants from local nurseries using seed of local provenance where possible. Supporting forest restoration projects that include this species helps ensure its long-term survival.