Cook's Scurvy Grass
Lepidium oleraceum
This native plant, known as Cook's Scurvy Grass(scientific name: Lepidium oleraceum ), 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 Browse All .
Plant Description
Identification and Physical Characteristics
Cook's Scurvy Grass ( Lepidium oleraceum ) is a perennial herb that forms a dense, leafy clump, typically growing up to 1 meter tall and wide. Its stems are much-branched and somewhat woody near the base. The leaves are dark green, fleshy, and somewhat succulent, ranging from narrow-oblanceolate to obovate or elliptic, with deeply and evenly serrated margins. When bruised, all parts of the plant emit a strong, pungent smell. It produces fragrant white flowers, sometimes yellow, with four stamens. These are followed by small, flattened, oval seed pods. This species is now largely restricted to offshore rock stacks and islets, as well as wind-swept headlands, often in friable, well-manured soils or guano deposits associated with seabird nesting sites.
Quick Facts
| Scientific Name | Lepidium oleraceum |
|---|---|
| Height | Up to 1 m |
| Spread | Up to 1 m |
| Water Needs | Moderate, well-drained coastal soil |
| Light | Full sun to partial shade |
| Frost Tolerance | Moderate; protect from hard frosts |
| Salt Tolerance | Very high; naturally adapted to coastal conditions |
| Growth Rate | Moderate |
| Lifespan | Perennial |
Climate Best Suited to
Lepidium oleraceum is well adapted to various New Zealand regions.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Auckland | High |
| Wellington | High |
| Christchurch | Medium |
Plant Habitat
Natural Occurrence and Ecology
Understanding the natural habitat of Cook-s Scurvy Grass ( Lepidium oleraceum ) is crucial for its conservation and any cultivation attempts. This species has very specific habitat requirements.Coastal cliffs, beaches, and offshore islands throughout New Zealand.Areas enriched by seabird colonies with high soil fertility.Maritime environments with salt spray and stable temperatures.
Growing Requirements
Soil Requirements
Prefers well-draining soil rich in organic matter.
- Well-drained
- Loamy
Light Requirements
Grows best in partial to full sun.
- Full Sun
- Partial Shade
Water Requirements
Requires regular watering during dry periods.
- Regular
- Drought tolerant once established
Planting and Establishing
Establishment Guidance
Plant Lepidium oleraceum in a hole twice the width of the root ball.
Proper establishment is key to long-term success. Ensure the planting hole is twice as wide as the root ball and backfill with a mix of native soil and organic compost. Initial watering should be thorough, followed by regular monitoring during the first two growing seasons to ensure the plant becomes well-anchored and resilient to local climate fluctuations.
Ecological Role
Biodiversity and Ecosystem Impact
Provides habitat and food for native fauna.
This species plays a vital role in its local ecosystem, providing essential habitat and food sources for native biodiversity. Its presence supports complex ecological interactions, contributing to the overall health and stability of the environment. By planting this native, you help maintain the intricate web of life that defines New Zealand's unique natural heritage.
Uses & Significance
Garden Uses
Ideal for rock gardens and native borders.
- Rock gardens
- Ground cover
Ecological Value
Supports local pollinators.
- Birds
- Insects
The versatility of this plant makes it a valuable addition to many New Zealand gardens. Beyond its aesthetic appeal, it offers practical benefits such as soil stabilization and shelter for smaller plants. Its historical and modern uses highlight its enduring importance in both traditional practices and contemporary landscape design, making it a thoughtful choice for any restoration or gardening project.
Landscaping Uses
Adds texture and form to modern landscapes.
In a landscape setting, this plant provides excellent structure and year-round interest. Its unique form and foliage can be used to create focal points or as a cohesive element in a larger native planting scheme. It pairs well with other New Zealand natives, allowing for the creation of diverse and resilient garden environments that reflect the natural beauty of Aotearoa.
Seasonal Care Calendar
Spring
Mulch and apply balanced fertilizer.
- Fertilize
- Mulch
Summer
Water deeply during dry spells.
- Water
- Check for pests
Autumn
Tidy up any dead foliage.
- Prune lightly
- Plant new specimens
Winter
Protect from heavy frosts if necessary.
- Frost protection
When to Prune and How Much
Minimal pruning required to maintain shape.
- Remove dead branches
Always use clean, sharp tools.
Regular maintenance through careful pruning ensures the plant remains healthy and maintains its desired shape. Focus on removing dead or diseased wood to promote better air circulation and prevent the spread of pathogens. Proper pruning techniques help the plant direct its energy toward new growth, resulting in a more robust and aesthetically pleasing specimen in your garden.
How to Grow Cook's Scurvy Grass
Cultivating Lepidium oleraceum ( Lepidium oleraceum ) 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 Lepidium Oleraceum 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.
Sow fresh seeds in a seed-raising mix.
- Collect seeds
- Sow in trays
Keep moist until germination.
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.
Take semi-hardwood cuttings in late summer.
- Take cuttings
- Use rooting hormone
Additional Methods
Depending on the growth habit of Lepidium oleraceum , other methods such as division or layering might also be viable options. Division is particularly suitable for plants that form dense clumps or have spreading root systems, while layering can be used for species with trailing or flexible stems.
Division can be done in early spring.
- Divide clumps
- Replant immediately
Pests & Diseases
Generally resistant to major pests.
While generally resilient, maintaining optimal growing conditions is the best defense against pests and diseases. Regular monitoring allows for early detection of any issues, which can often be managed through cultural practices or organic interventions. Ensuring good air circulation and appropriate watering will significantly reduce the plant's susceptibility to common environmental stresses and pathogens.
Cultural Significance
Lepidium oleraceum , commonly known as Cook's scurvy grass or by its Māori names nau, ngau, naunau, and heketara, holds significant cultural and historical importance, particularly in New Zealand.Māori Traditional Use:The Māori people traditionally consumed the young leaves of Lepidium oleraceum raw or cooked. The Māori name "nau" is ancient and found in various forms throughout Polynesia, suggesting that many Pacific Island peoples traditionally harvested or cultivated related lepidia as a vegetable.Captain Cook's Voyages:The plant gained widespread recognition during Captain James Cook's voyages of exploration in the late 1700s and early 1800s. Cook noted in his journal in 1769 that he collected "Sellery and Scurvy grass" (believed to be Lepidium oleraceum ) to help ward off scurvy among his crew. Its high vitamin C content made it valuable in preventing this deficiency disease.Once widespread in coastal areas of New Zealand, Lepidium oleraceum is now considered nationally vulnerable or endangered due to various threats, including habitat loss, browsing by livestock and pests, and reduced seabird populations, which it relies on for fertile soil.
- Traditional medicine
- Crafts
Bonus Tip
Excellent for low-maintenance gardens.
For an extra boost, consider applying a thin layer of high-quality organic mulch around the base of the plant. This helps retain soil moisture, suppresses weeds, and gradually improves soil structure as it breaks down. This simple step can make a significant difference in the plant's overall vigor and resilience, especially during periods of extreme weather.
Related Plants
Explore other native plants that share similar characteristics or habitats with Lepidium Oleraceum ( Lepidium oleraceum ), offering further insights into New Zealand's diverse flora. These related species provide context and opportunities for complementary planting in your garden.
Plant Conservation
Conservation Status
Lepidium oleraceum , commonly known as Cook's scurvy grass, nau, ngau, naunau, or heketara, is a herb endemic to New Zealand and is classified as "Nationally Vulnerable" (NZ TCS). Once widespread, its populations have significantly declined over the last 150 years and are now mostly restricted to offshore rock stacks and islets, such as Mana Island, to protect them from threats. The plant faces numerous threats to its survival: reduced seabird populations (which it depends on for fertile and disturbed soils), browsing by livestock, rodents, and snails, insect herbivores (aphids, leaf miners, diamondback moth, small cabbage white butterfly), diseases (white rust), habitat deterioration due to human activity and coastal development, and historically, over-collecting by botanists. Conservation efforts are underway, including a Coastal Cresses Recovery Plan approved in 1998 by the Department of Conservation (DOC). This plan aims to restore viable and self-sustaining populations of all extant coastal cress species throughout their natural range. The plan also emphasizes the need for increased monitoring of coastal cress populations and addresses unresolved taxonomic issues within the Lepidium species group, which have implications for their conservation status and management.