<i>Olearia adenocarpa</i>(Olearia adenocarpa) hero image

Dryland Tree Daisy

Olearia adenocarpa

Nationally Critical

The Dryland Tree Daisy (Olearia adenocarpa) is a critically endangered shrub endemic to the Canterbury Plains of New Zealand. Known for its distinct grey-green foliage and habit of growing in braided riverbeds, it is a key species for conservation.

Dryland Tree Daisy (Olearia adenocarpa) in its native New Zealand dryland habitat
Image credit: Dryland Tree Daisy (O. adenocarpa) - Photo via Wikipedia

Plant Description

Identification and Physical Characteristics

Olearia adenocarpa is a deciduous to semi-deciduous shrub that typically reaches a height of 1.5 to 2 metres and a similar spread Discover more about native shrubs. It exhibits a low, spreading, and notably open growth habit, often with branches that run along the ground (decumbent) before turning upwards at the tips. A unique characteristic of this species is its ability to regularly produce new branches from or below ground level, which replace older main branches that typically have a lifespan of about 12 years. The leaves are small, egg-shaped (ovate), measuring 3 to 14 millimetres in length and 2 to 4 millimetres in width. They are a distinctive grey-green colour on the upper surface, while the underside is covered in a dense layer of fine, white hairs. In January and February, the plant produces clusters of pale white flowers with bright yellow or green centers. The seeds are dry and covered in hairs, a key trait that helps distinguish this species from other small-leaved Olearias.

Quick Facts

Olearia adenocarpa quick facts
Scientific Name Olearia adenocarpa
Height 1.5-2.0 metres
Spread 1.2-2.0 metres
Water Needs Low (Drought tolerant)
Light Full Sun
Frost Tolerance High (Hardy)
Salt Tolerance Low
Growth Rate Medium
Lifespan Perennial (Individual branches ~12 yrs)

Climate Best Suited to

Olearia adenocarpais well adapted to various New Zealand regions.

Regional Suitability

City suitability for Olearia adenocarpa
City Climate Suitability
Auckland High
Wellington High
Christchurch Medium

Plant Habitat

Natural Occurrence and Ecology

Olearia adenocarpais an extreme specialist, endemic to a very restricted area of the Canterbury Plains. Its natural habitat consists of dry, stony terraces and abandoned channels bordering braided riverbeds. It grows specifically in recently deposited alluvial gravels and sands-environments that are nutrient-rich (particularly in phosphorus) but highly prone to severe summer drought. These habitats are often open and wind-swept, where the plant's low-growing habit protects it from the worst of the elements. It is currently known from only two small wild populations located along the Waimakariri and Rakaia rivers.

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 Olearia adenocarpain 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 Dryland Tree Daisy

Cultivating Olearia adenocarpa(Olearia adenocarpa) 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 Olearia Adenocarpa 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 Olearia adenocarpa, 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

While specific records are limited for this species,Olearia adenocarpasits within a wider native plant tradition valued for its ecological role and local stewardship.

  • 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

Currently classified as "Nationally Critical,"Olearia adenocarpais on the absolute brink of extinction in the wild. Fewer than 650 individual plants are known to remain. The primary threats are habitat loss through land conversion to farming and the fragmentation of the rare river-terrace ecosystems it requires. Browsing by hares, rabbits, and livestock is a major issue, as it destroys young seedlings and prevents natural recruitment. Competition from aggressive exotic weeds like wild thyme also displaces the native daisy. Conservation efforts are intensive, involving the fencing of remaining wild sites, ongoing predator control, and large-scale propagation programs to reintroduce the species to safe, managed habitats.