<i>Pittosporum crassifolium</i>(Pittosporum crassifolium) hero image

Kāro

Pittosporum crassifolium

Not specified

This native plant, known as Kāro (scientific name: Pittosporum crassifolium ), 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 .

<i>Pittosporum crassifolium</i>(Pittosporum crassifolium) showing <i>Pittosporum crassifolium</i>growth habit
Image credit: Kāro ( Pittosporum crassifolium ) - Photo via Wikipedia

Plant Description

Identification and Physical Characteristics

Kāro ( Pittosporum crassifolium ), also known as Stiffleaf Cheesewood, Kaikaro, or Kihikihi, is an evergreen shrub or small tree native to New Zealand Discover more about native grasses. It typically grows to 5-10 meters tall and 3-4 meters wide, with an upright, bushy habit. Its name "crassifolium" is Latin for "thick leaf," referring to its distinctive foliage. The leaves are oval to obovate or oblanceolate, 5-10 cm long and 2-3 cm wide, leathery, dark green on the upper surface, and covered with dense whitish or buff-coloured fine hairs (tomentum) on the undersides and petioles. This tomentum helps protect against salt damage and moisture loss in coastal environments. The leaf margins are often recurved and entire. During spring to early summer (August to October), it produces fragrant, squat-campanulate (bell-shaped) flowers. These flowers are typically dark burgundy red to deep red, though rarely white in New Zealand, and are borne in terminal clusters. Following the flowers, hard green capsules develop into seed pods. These capsules are spheroidal or obloid, 15-25 mm long, pale grey-green, and densely tomentose. When ripe, typically in late autumn or September, the capsule splits into three or four woody valves, revealing numerous sticky black seeds embedded in a yellow pith.

Quick Facts

Pittosporum crassifolium quick facts
Scientific Name Pittosporum crassifolium
Height 3-10 m
Spread 2-6 m
Water Needs Low to moderate
Light Full sun to partial shade
Frost Tolerance Moderate when mature
Salt Tolerance Excellent
Growth Rate Fast
Lifespan Long-lived

Climate Best Suited to

Pittosporum crassifolium is well adapted to various New Zealand regions.

Regional Suitability

City suitability for Pittosporum crassifolium
City Climate Suitability
Auckland High
Wellington High
Christchurch Medium

Plant Habitat

Natural Occurrence and Ecology

Kāro ( Pittosporum crassifolium ), also known as Stiffleaf Cheesewood, Kaikaro, or Kihikihi, is an evergreen shrub or small tree endemic to New Zealand. Its natural habitat primarily consists of coastal areas and offshore islands, particularly the Great Barrier and North Islands, extending south to about White Cliffs and East Cape.Coastal Environments:It thrives on steep slopes, cliff faces, boulder beaches, rock stacks, and the margins of petrel-burrowed land, showcasing its exceptional adaptation to harsh coastal conditions.Dune Forests and Forest Margins:Kāro can also be a significant component of dune forests and is found along forest margins and streams in coastal localities.Resilience:This species is remarkably tolerant of high winds, salt spray, drought, and even moderate frosts once established. The fine hairs on the underside of its leaves help reduce salt damage and prevent moisture loss, allowing it to thrive in these challenging environments.Endemic to North Island and Offshore Islands:While endemic to the North Island and its offshore islands, due to bird dispersal of its sticky seeds, it has become widely naturalized further south in New Zealand (South, Stewart, and Chatham Islands) and even in Norfolk Island and Hawaii. In these non-endemic areas, it is sometimes considered an urban weed due to its prolific spread.Kāro's ability to colonize and thrive in exposed coastal environments underscores its ecological importance in stabilizing vulnerable areas and providing habitat in challenging conditions.

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 Pittosporum crassifolium 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 Kāro

Cultivating Pittosporum crassifolium ( Pittosporum crassifolium ) 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 Pittosporum crassifolium 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 Pittosporum crassifolium , 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

Pittosporum crassifolium , commonly known as Kāro, holds significant cultural importance, particularly for the Māori people of New Zealand, where it is native.Traditional Māori Uses:The Māori have historically utilized Kāro for practical purposes, including crafting tools, weapons, and musical instruments. Its dense and durable wood was also valued for carving and construction. The wood and leaves were also used for medicinal purposes.Symbolism:The fragrant flowers of Kāro are associated with love and romance. More broadly, the plant symbolizes resilience and protection due to its ability to thrive in harsh coastal environments. Its tough leaves and hardy nature represent endurance and safeguarding, embodying the strength and perseverance of the Māori people.Spiritual Value:Beyond its practical applications, Kāro is cherished in Māori culture for its spiritual significance.Metaphorical Representation:The plant's resilience has led to its use as a metaphor for enduring difficult circumstances in literature and art. It is also incorporated into special events that celebrate strength and milestones, and as a symbolic gift for housewarmings, representing a safe and resilient home.A dark blue dye can be extracted from its seeds.It is a source of saponins, which have been used as soap and as a bird deterrent.Its tough wood is also used for inlay.Due to its tolerance to pruning and maritime exposure, it is often used for protective hedges and for stabilizing sandy soils and dunes.

  • 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

Pittosporum crassifolium , also known as kāro, stiffleaf cheesewood, kaikaro, or kihiki, is classified as "Not Threatened" in its native New Zealand. This conservation status has been consistent, with records showing it as "Not Threatened" in 2023, 2017, 2012, 2009, and 2004.While not threatened in its endemic range, the species is noted to be widely naturalized in other areas, including the South, Stewart, and Chatham Islands of New Zealand, as well as Norfolk Island and Hawaii. In some of these non-native regions, it can be considered an "urban weed" due to its prolific dispersal by birds. It is also regarded as a potential environmental weed in parts of southeastern Australia.Threats to Pittosporum crassifolium in its native habitat include rats eating its fruits, which can hinder regeneration on rodent-infested offshore islands.