Coastal Tutu
Coriaria sarmentosa
Coriaria sarmentosa , commonly known as the Coastal Tutu or Trailing Tutu, is a spreading native shrub endemic to New Zealand. Unlike its tree-sized relative Coriaria arborea , `C. sarmentosa` typically grows as a smaller, more sprawling plant, adapting well to coastal and open environments. Similar to other Tutu species, it is highly toxic, with all parts containing the neurotoxin tutin, particularly the seeds. Despite its poisonous nature, it plays an important ecological role and is a visually attractive plant with its delicate foliage and distinctive fruit.
Plant Description
Coriaria sarmentosa is a deciduous to semi-deciduous spreading shrub, typically growing up to 1-2 meters tall and often sprawling widely. Its stems are slender, reddish, and somewhat arching, often forming dense thickets. The leaves are opposite, elliptic to ovate, fresh green, and can turn reddish in autumn before dropping in colder areas. In spring, it produces inconspicuous green flowers in pendulous racemes, which are followed by vibrant, fleshy "berries" that ripen from red to glossy black in late summer to autumn. These "berries," like those of other Tutu species, are actually enlarged petals enclosing the toxic seeds.
Quick Facts
| Scientific Name | Coriaria sarmentosa |
|---|---|
| Family | Coriariaceae |
| Form | Deciduous to semi-deciduous spreading shrub |
| Light | Full sun to partial shade |
| Soil | Well-drained, tolerant of poor soils |
| Water | Moderate, tolerant of some drought once established |
| Water Needs | Moderate |
| Frost Tolerance | Hardy |
| Salt Tolerance | Moderate |
| Height | 1-2 m |
| Spread | 1.5-3 m |
| Flowering Season | Spring |
| Fruit/Berry Season | Late summer to autumn |
| Foliage | Deciduous in colder areas; fresh green, elliptic leaves |
| Growth Rate | Moderate to fast |
| Lifespan | Perennial |
| Toxicity | Highly poisonous (all parts, especially seeds) |
Climate Best Suited to
Coriaria sarmentosa prefers cooler, moister conditions than its relative C. arborea, thriving in forest margins and stream sides. Native to areas with consistent moisture and partial shade, it performs best in regions with 1000-2000mm annual rainfall and temperatures between 0-25°C. This species requires protection from drought and extreme heat.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Whangārei | Suitable |
| Auckland | Suitable |
| Hamilton | Suitable |
| Tauranga | Suitable |
| Rotorua | Ideal |
| Gisborne | Marginal |
| New Plymouth | Ideal |
| Napier | Marginal |
| Whanganui | Suitable |
| Palmerston North | Suitable |
| Wellington | Ideal |
| Nelson | Ideal |
| Christchurch | Suitable |
| Dunedin | Ideal |
| Invercargill | Suitable |
Habitat
Natural Distribution
Coriaria sarmentosa is commonly found in coastal areas, open scrubland, riverbeds, and forest margins throughout New Zealand. It often grows on sandy or gravelly soils, where its spreading habit helps to stabilize disturbed ground. Its presence is indicative of regenerating ecosystems, and it can form dense colonies in suitable habitats.
Conservation Status
Current Threats and Protection
Coriaria sarmentosa is classified as "Not Threatened" under the New Zealand Threat Classification System. It is a common and widespread species with stable populations in appropriate habitats. Its ecological resilience ensures its continued presence in New Zealand's diverse landscapes.
How to Grow
Cultivation Requirements
Due to its high toxicity, Coriaria sarmentosa is generally not recommended for cultivation in domestic gardens, especially where children, pets, or livestock are present. If grown in controlled environments for ecological restoration or botanical study, it requires full sun to partial 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. Always exercise extreme caution when handling this plant.
Planting Guide
Best Planting Practices
Planting of Coriaria sarmentosa should be limited to large-scale ecological restoration projects or very isolated, wild natural areas where public access is restricted. Choose an open, sunny to partially shaded position with free-draining soil. Dig a planting hole twice the width of the root ball and the same depth. Handle with protective gloves. Water well during establishment. Due to its sprawling habit, ensure it has ample space to spread without encroaching on paths or other plants of concern.
Ecological Role
Environmental Benefits
Coriaria sarmentosa plays a significant ecological role in its native habitats. It is a nitrogen-fixing plant, thanks to symbiotic bacteria in its root nodules, which enhances soil fertility and supports the growth of other plant species, particularly in nutrient-poor or disturbed soils. Its fruit, while toxic to mammals, is a food source for native birds, which are immune to the tutin toxin and act as vital seed dispersers, aiding in forest regeneration.
Uses
Traditional and Modern Applications
Historically, Māori cautiously extracted a non-toxic juice from the berries of Tutu species (after removing the poisonous seeds) for various purposes. Today, Coriaria sarmentosa is primarily valued for its ecological benefits in revegetation, particularly for erosion control and soil stabilization in coastal and riparian areas. Its nitrogen-fixing capability makes it useful in improving degraded soils. Due to its extreme toxicity, it is not recommended for general garden use.
Landscaping Uses
Garden Design Applications
Given its highly poisonous nature, Coriaria sarmentosa is typically not used in conventional landscaping. However, in extensive ecological restoration sites or large, wild natural areas with restricted access, its spreading growth habit can be effectively utilized for groundcover, erosion control on slopes, or to stabilize sand dunes. Its attractive seasonal foliage and fruit can add visual interest to such specialized landscapes.
Seasonal Care
Year-Round Maintenance
Coriaria sarmentosa requires minimal seasonal care once established. Water only during prolonged dry periods, especially for young plants. Pruning, if necessary, should be done in late winter or early spring to manage its size or remove dead/damaged wood. Due to its toxicity, always wear gloves and protective clothing when handling the plant, and thoroughly clean tools afterward.
Pruning
Pruning Techniques
Prune Coriaria sarmentosa in late winter or early spring to maintain shape, control spread, or remove any dead or damaged stems. Its sprawling habit may necessitate occasional trimming to keep it within bounds. Always wear protective gloves and long sleeves due to the plant's toxicity. Dispose of all pruned material carefully, ensuring it cannot be ingested by animals or children.
How to Grow Coastal Tutu
From Seed
Propagation of Coriaria sarmentosa 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 sarmentosa can be successfully propagated from semi-hardwood cuttings. Take cuttings about 10-15 cm long from healthy, non-flowering shoots in late summer or early autumn. Remove the lower leaves and dip the cut end in 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 sarmentosa is a spreading native shrub adapted to coastal and disturbed environments. Due to its extreme toxicity, it is generally not recommended for cultivation in domestic gardens, especially where children, pets, or livestock are present. If grown for ecological restoration or in very large, isolated natural areas, it requires full sun to partial shade and well-drained soil. It is remarkably tolerant of poor soil conditions (sandy or gravelly) 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 any dead or crossing material to maintain its shape or control spread. 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 sarmentosa is generally a robust plant with few significant pest or disease problems when grown in suitable conditions. The most common issues, if any, are typically related to poor drainage leading to root rot. Its inherent toxicity may deter some common garden pests. Ensure well-drained soil and adequate air circulation to maintain plant health.
Cultural Significance
Traditional Uses and Values
Coriaria sarmentosa , like other Tutu species, holds a prominent and complex place in New Zealand's natural and cultural history. While its toxicity is well-known, Māori traditionally developed methods to extract a non-poisonous juice from the berries, demonstrating a deep understanding of the plant's properties. Its presence in coastal and disturbed areas made it a familiar component of the landscape for both Māori and early European settlers. It contributes to the rich botanical heritage and unique ecological story of Aotearoa.
Bonus Tip
Expert Growing Advice
Remember that all parts of Coriaria sarmentosa are highly toxic. If you encounter this plant in its natural habitat or in a specialized botanical collection, observe its beauty from a safe distance and never attempt to consume any part of it.
