Native Broom (Carmichaelia australis) hero image

Common Native Broom

Carmichaelia australis

Not specified

This native plant, known as Common Native Broom (scientific name: Carmichaelia australis ), 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 .

Native Broom (Carmichaelia australis) showing its unique photosynthetic stems
Image credit: Common Native Broom ( Carmichaelia australis ) - Photo via Wikipedia

Plant Description

Identification and Physical Characteristics

Carmichaelia australis , commonly known as New Zealand common broom or mākaka, is an endemic shrub belonging to the Fabaceae family Discover more about native shrubs. It is found throughout New Zealand, particularly in lowland and mid-montane sites, often in shrublands and forest margins.This hardy, fast-growing plant typically ranges from a small to large shrub, growing between 1-2 meters, though it can reach 2-8 meters in height and 2-5 meters in spread. A distinguishing feature of Carmichaelia australis is its flattened to round photosynthetic stems (cladodes), which are green, yellow-green, or brown-green and take in sunlight, largely replacing the need for leaves. While seedlings and young plants may have small leaves with three to five leaflets, these are typically absent in adult plants.From spring through summer, it produces small (5-6 mm) white flowers, often with purple veins and sometimes purple centers. These flowers are attractive to insects and bees. The fruit appears from November to May as small, dry, oblong pods, 6.5-15 mm long, which contain 1-5 seeds. The seeds are typically yellow, orange, or red, sometimes with black dots, and are distributed when the seedpod bursts. Carmichaelia australis prefers full sunlight and well-drained soil, tolerating dry, windy, and cold conditions down to -7 °C. It is drought-tolerant once established but cannot withstand waterlogging for extended periods. As a member of the Fabaceae family, it is a nitrogen-fixing species, forming a symbiotic relationship with Rhizobia bacteria in its root nodules, which enhances soil fertility.

Quick Facts

Carmichaelia australis quick facts
Scientific Name Carmichaelia australis
Height 2-5 m
Spread 2-8 m
Water Needs Low once established
Light Full sun to light shade
Frost Tolerance High
Salt Tolerance Moderate
Growth Rate Moderate
Lifespan Long-lived shrub

Climate Best Suited to

Carmichaelia australis is well adapted to various New Zealand regions.

Regional Suitability

City suitability for Carmichaelia australis
City Climate Suitability
Auckland High
Wellington High
Christchurch Medium

Plant Habitat

Natural Occurrence and Ecology

Carmichaelia australis , also known as New Zealand common broom, is a shrub endemic to New Zealand, found across both the North and South Islands, though not in the southern South Island. It exhibits a broad ecological niche, thriving in a variety of environments from coastal to inland sites, and from lowland to montane areas. Its natural habitat includes river terraces, stony flats, stream banks, colluvium inclines, rock outcrops, talus, fan toe slopes, tussock grasslands, edges and margins of dense bush and forest, and around swamps. It prefers free-draining, low to moderately fertile soils, including stony, sandy, or gravelly sites, and avoids prolonged waterlogging and heavy clays.

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 Carmichaelia australis 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 Common Native Broom

Cultivating Carmichaelia australis ( Carmichaelia australis ) 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 Carmichaelia australis 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.

  1. Collect seeds
  2. 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.

  1. Take cuttings
  2. Use rooting hormone

Additional Methods

Depending on the growth habit of Carmichaelia australis , 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.

  1. Divide clumps
  2. 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

Native Broom ( Carmichaelia australis ) was used by Māori for various purposes. The tough, flexible stems were used for weaving and construction, and the plant also had medicinal uses in rongoā (traditional Māori medicine).

  • 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.

Plant Conservation

Conservation Status

Native Broom ( Carmichaelia australis ) is currently classified as "Not Threatened" nationally in New Zealand, reflecting its widespread distribution and adaptability across various habitats. However, it is listed as "At Risk - Declining" in several regions, such as Auckland, due to habitat loss and browsing pressure from introduced animals.Conservation efforts focus on protecting its natural habitats, controlling invasive species, and promoting its use in restoration plantings. Its ability to fix nitrogen makes it valuable for improving soil fertility in degraded areas.