Tutu
Coriaria arborea
Coriaria arborea , commonly known as Tutu, is a large, fast-growing native shrub or small tree endemic to New Zealand. It is perhaps best known for being one of New Zealand's most poisonous plants, with all parts, especially the seeds, containing the neurotoxin tutin. Despite its toxicity, Tutu plays a significant ecological role and is a visually striking plant with its graceful arching stems, lush foliage, and distinctive fruit clusters. The vibrant red-black "berries" (actually fleshy petals) are a familiar sight in many New Zealand landscapes.
Plant Description
Coriaria arborea typically grows as a multi-stemmed shrub or small tree, reaching 2 to 8 meters in height, though it can sometimes grow larger. It features distinctively paired, opposite leaves that are bright green, ovate to heart-shaped, and often have prominent veins. The stems are reddish-brown and often arch gracefully. In spring and early summer, it produces long, drooping racemes (spikes) of inconspicuous greenish flowers. These are followed by very showy, succulent "berries" that ripen from red to glossy black in late summer and autumn. These "berries" are actually enlarged and fleshy petals that enclose the true seeds.
Quick Facts
| Scientific Name | Coriaria arborea |
|---|---|
| Family | Coriariaceae |
| Form | Multi-stemmed shrub or small tree |
| Light | Full sun to light shade |
| Soil | Well-drained, tolerant of various soil types |
| Water | Moderate, tolerant of some drought once established |
| Water Needs | Moderate |
| Frost Tolerance | Hardy |
| Salt Tolerance | High |
| Height | 2-8 m |
| Spread | 1.5-4 m |
| Flowering Season | Spring to early summer |
| Fruit/Berry Season | Late summer to autumn |
| Foliage | Deciduous in cooler areas, evergreen in mild climates; bright green, ovate leaves |
| Growth Rate | Fast |
| Lifespan | Long-lived perennial |
| Toxicity | Highly poisonous (all parts, especially seeds) |
Climate Best Suited to
Coriaria arborea is highly adaptable, occurring from sea level to montane zones throughout New Zealand. This pioneer species tolerates a wide temperature range (-5°C to 30°C) and various rainfall patterns. It thrives in disturbed sites with full sun to partial shade, performing best in areas with 800-2000mm annual rainfall and well-drained soils.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Whangārei | Ideal |
| Auckland | Ideal |
| Hamilton | Ideal |
| Tauranga | Ideal |
| Rotorua | Ideal |
| Gisborne | Suitable |
| New Plymouth | Ideal |
| Napier | Suitable |
| Whanganui | Ideal |
| Palmerston North | Ideal |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Suitable |
| Dunedin | Suitable |
| Invercargill | Marginal |
Habitat
Natural Distribution
Coriaria arborea is widespread throughout New Zealand, found in diverse habitats from lowland forests and forest margins to shrubland, riverbeds, and open disturbed areas. It is a common pioneer species, readily colonizing clearings, roadsides, and regenerating bush. It often grows alongside other native shrubs and trees, forming dense thickets. Its ability to thrive in disturbed areas makes it a significant component of many regenerating ecosystems.
Conservation Status
Current Threats and Protection
Coriaria arborea is classified as "Not Threatened" under the New Zealand Threat Classification System. It is a common and widespread species with stable populations throughout its range. Despite its toxic nature, its ecological resilience ensures its continued presence in New Zealand's natural landscapes.
How to Grow
Cultivation Requirements
Despite its common occurrence, Coriaria arborea is generally not recommended for cultivation in domestic gardens due to its extreme toxicity, particularly around children and livestock. If grown, it requires a site with full sun to light shade and well-drained soil. It is tolerant of poor soil conditions and does not require rich, fertile ground. Once established, it is relatively drought-tolerant, but regular watering during prolonged dry spells will promote healthier growth. Avoid planting where its fallen berries or accessible foliage could pose a risk.
Planting Guide
Best Planting Practices
Planting of Coriaria arborea should only be considered in isolated restoration projects or very large, wild natural areas, away from human habitation and livestock. Choose a sunny or lightly shaded position with well-drained soil. Dig a hole twice the width of the root ball and the same depth. Handle with gloves. Water well during establishment. Due to its fast growth, ample space should be provided. Extreme caution is advised if planted in any area where it could be encountered by people or animals.
Ecological Role
Environmental Benefits
Coriaria arborea plays a crucial ecological role in New Zealand. It is a nitrogen-fixing plant, thanks to symbiotic bacteria in its root nodules, which enriches the soil and aids the growth of other plants, particularly in disturbed or poor soils. Its fruit is a significant food source for native birds, which are immune to the tutin toxin and act as seed dispersers. This makes it a vital component of forest regeneration and a key species in maintaining healthy native ecosystems.
Uses
Traditional and Modern Applications
Historically, Māori extracted a non-toxic juice from the berries, which was then fermented into a beverage or made into jellies, after careful removal of the poisonous seeds. Today, Coriaria arborea is primarily valued for its ecological benefits in revegetation and land stabilization. Its nitrogen-fixing ability makes it useful in restoring degraded soils, and its rapid growth can provide quick cover. Due to its high toxicity, it is not recommended for general garden use.
Landscaping Uses
Garden Design Applications
Due to its highly poisonous nature, Coriaria arborea is generally unsuitable for typical landscaping in populated areas. However, in large-scale ecological restoration projects or very extensive, wild native gardens where public access is restricted, its fast-growing, graceful form and attractive fruit can provide valuable visual interest and ecological function. It can be used for erosion control on slopes and to provide shelter for establishing slower-growing native species.
Seasonal Care
Year-Round Maintenance
Coriaria arborea requires minimal care once established. Water only during prolonged dry periods, particularly for young plants. Pruning can be done in late winter to early spring to manage its size or remove any dead/damaged wood. Given its toxicity, always wear gloves and protective clothing when handling the plant, and wash tools thoroughly afterward.
Pruning
Pruning Techniques
Prune Coriaria arborea in late winter or early spring to control its size, improve its shape, or remove any dead, diseased, or crossing branches. Due to its fast growth, it can be pruned quite hard if necessary to maintain a desired form. Always wear protective gloves and long sleeves due to the plant's toxicity. Dispose of all pruned material carefully, ensuring it cannot be accidentally ingested by animals or children.
How to Grow Tutu
From Seed
Propagation of Coriaria arborea from seed is a common method, particularly as it is a pioneer species. Collect ripe berries (drupes) in late summer to autumn. It is crucial to handle all plant parts with extreme care due to their high toxicity. Clean the fleshy pulp from the seeds, as this can inhibit germination. Tutu seeds often benefit from a period of cold stratification (4-8 weeks in a refrigerator) to break dormancy, mimicking natural winter conditions. Sow pre-treated seeds onto a well-draining seed-raising mix, lightly covering them. Maintain consistent moisture and provide cool to moderate temperatures (around 10-18°C or 50-65°F) in a well-ventilated location. Germination can be erratic, taking several weeks to months. Once seedlings are robust enough to handle, prick them out into individual pots and grow them on in a sheltered, bright location until strong enough for planting out.
From Cuttings
Coriaria arborea can be successfully propagated from semi-hardwood cuttings. Take cuttings about 10-15 cm long from healthy, non-flowering stems in late summer or early autumn. Remove the lower leaves and dip the cut end in a rooting hormone to encourage root development. Insert the cuttings into a free-draining rooting medium such as a mix of sand and perlite. Maintain high humidity around the cuttings, either by placing them in a propagation chamber or covering them with a plastic bag, and ensure consistent moisture in the rooting medium. Keep in a warm, bright location out of direct sunlight. Rooting typically occurs within 6-12 weeks. Once rooted, gradually acclimatize plants to ambient conditions before potting up. Always handle cuttings with gloves due to the plant's toxicity.
General Cultivation
Coriaria arborea is a vigorous and adaptable native shrub or small tree. Due to its extreme toxicity, particularly around children and livestock, it is generally not recommended for cultivation in domestic gardens. If grown for ecological restoration or in very large, isolated natural areas, it requires full sun to light shade and well-drained soil. It is remarkably tolerant of poor soil conditions and does not require rich, fertile ground. Once established, it is relatively drought-tolerant, but regular watering during prolonged dry spells will promote healthier growth. Avoid planting where its fallen berries or accessible foliage could pose a risk to humans or animals. Minimal pruning is required; remove dead or crossing material to maintain its shape or control size. Always wear gloves and protective clothing when handling any part of the plant, and dispose of pruned material carefully to prevent accidental ingestion.
Pests and Diseases
Common Problems and Solutions
Coriaria arborea is generally a hardy plant with few significant pest or disease problems. Its toxicity may deter some herbivores. Occasionally, it may be affected by common fungal diseases if conditions are too damp or air circulation is poor. Ensure well-drained soil and adequate spacing to promote plant health. The primary concern with this plant is its inherent toxicity rather than susceptibility to external threats.
Cultural Significance
Traditional Uses and Values
Coriaria arborea , or Tutu, holds a complex and significant place in both Māori culture and New Zealand history. Known to Māori as "Tutu," its berries provided a valued, albeit carefully processed, food source and a dye, while other parts were used medicinally with extreme caution. Its widespread presence made it a notable feature of the landscape. Early European settlers quickly learned of its potent toxicity, which caused significant livestock poisoning and even human fatalities. This dual nature - a source of sustenance and danger - has embedded Tutu deeply in the cultural fabric and folklore of New Zealand, making it one of the most recognized and respected native plants.
Bonus Tip
Expert Growing Advice
While the fruit of the Tutu plant may look appealing, all parts of Coriaria arborea , especially the seeds contained within the fleshy "berries," are highly poisonous to humans and many animals. Exercise extreme caution and never ingest any part of the plant.
