Cushion Daisy
Abrotanella caespitosa
Abrotanella caespitosa is one of New Zealand's most remarkable alpine cushion plants, forming incredibly compact, dome-shaped mounds that appear almost moss-like from a distance. Endemic to the South Island's high mountains, this tiny member of the daisy family (Asteraceae) has evolved extraordinary adaptations to survive in some of the harshest environments in New Zealand. Found primarily above 1500 meters elevation in the Southern Alps, Central Otago mountains, and Fiordland ranges, it creates living carpets across exposed fellfields, rocky ridges, and stable scree slopes. The cushion form, which can take decades to reach just 30 centimeters across, represents one of nature's most effective strategies for surviving extreme cold, desiccating winds, and intense UV radiation. Each cushion consists of thousands of tightly packed shoots, creating a microenvironment that can be several degrees warmer than the surrounding air. This remarkable plant belongs to a select group of New Zealand's specialized alpine plants that have adapted to life above the treeline.
Plant Description
The growth form of Abrotanella caespitosa represents a masterclass in alpine adaptation. The plant develops as an extremely compact, hemispherical cushion, rarely exceeding 3 centimeters in height but potentially spreading to 40 centimeters in diameter over many decades. Individual shoots are densely packed, with internodes so short they are practically invisible. The leaves are minute, typically 2-4 millimeters long and less than 1 millimeter wide, narrowly linear to subulate (awl-shaped), and closely appressed to the stem. This creates a firm, almost rigid surface that feels springy to the touch, much like a well-stuffed pin cushion.
The leaf surfaces are covered in minute hairs (trichomes) that help trap moisture and reduce water loss, while the thick cuticle provides additional protection against UV radiation and desiccation. The entire cushion is anchored by a deep, woody taproot that can penetrate surprisingly far into rocky crevices, accessing moisture and providing stability against the fierce alpine winds that can exceed 200 kilometers per hour.
Flowering occurs from December to February, though blooms are easily overlooked. The flower heads (capitula) are solitary or in small clusters, sitting almost flush with the cushion surface. Each head is only 3-5 millimeters across, lacking the showy ray florets typical of many daisies. Instead, they consist solely of tiny disc florets, pale yellow to cream in colour. The flowers are functionally dioecious, with separate male and female plants, though hermaphrodite flowers also occur. Pollination is primarily by small alpine flies and beetles that shelter within the cushion structure. The seeds (technically cypselae) are minute, about 1-2 millimeters long, with a small pappus of bristles that aids in wind dispersal, though most seeds fall within a meter of the parent plant.
Quick Facts
Plant Specifications
| Scientific Name | Abrotanella caespitosa |
|---|---|
| Family | Asteraceae (daisy family) |
| Height | 1-3 cm |
| Growth Form | Very low, tight cushion; spreading to 20-40 cm across over time |
| Foliage | Minute, appressed, scale-like leaves densely packed on short shoots |
| Flowers | Tiny, inconspicuous heads without showy rays; summer |
| Light | Full sun; high light |
| Soil | Sharp drainage; gritty, low-organic, mineral substrates |
| Hardiness | Frost hardy if dry; intolerant of winter wet and summer heat |
| Water Needs | Low; avoid waterlogging |
| Spread | 20-40 cm (slowly) |
| Frost Tolerance | High |
| Salt Tolerance | Low to moderate |
| Growth Rate | Fast |
| Lifespan | Long-lived perennial |
Climate Best Suited to
Naturally a plant of exposed alpine and subalpine zones, thriving where winters are cold, snowfall is common, air is moving, and soils drain freely. Best suited to cool-summer climates. In lowland gardens it benefits from an alpine trough, rock crevice, or raised scree bed that sheds water quickly.
Regional Suitability
| City | Climate Suitability |
|---|---|
| Queenstown | Ideal |
| Wānaka | Ideal |
| Twizel | Ideal |
| Christchurch | Moderate |
| Wellington | Moderate |
| Auckland | Marginal |
| Whangārei | Marginal |
| Dunedin | Excellent |
| Hamilton | Challenging - requires cool conditions |
| Tauranga | Challenging - requires cool conditions |
| Napier | Challenging - requires cool conditions |
| Palmerston North | Good |
| Nelson | Good |
| Invercargill | Excellent |
| New Plymouth | Challenging - requires cool conditions |
| Rotorua | Challenging - requires cool conditions |
| Whangarei | Challenging - requires cool conditions |
| Gisborne | Suitable |
| Whanganui | Suitable |
Plant Habitat
Abrotanella caespitosa inhabits some of New Zealand's most extreme terrestrial environments, typically found between 1500 and 2300 meters elevation, though occasionally descending to 1200 meters in the southern ranges. It thrives in exposed fellfields, wind-scoured ridges, and stable rocky outcrops where few other plants can establish. These habitats are characterized by extreme temperature fluctuations - from below -15°C in winter to over 40°C on the cushion surface in summer sunshine.
The species shows a strong preference for sites with skeletal soils derived from schist, greywacke, or granite, where pH typically ranges from 5.5 to 7.0. These soils are extremely low in organic matter, often less than 2%, and consist primarily of mineral particles ranging from coarse sand to small stones. Despite the apparent barrenness, these soils are surprisingly rich in essential minerals leached from the parent rock.
The cushion form itself creates a remarkable microhabitat. Research has shown that temperatures within the cushion can be 15-20°C warmer than ambient air temperature on sunny days, while remaining several degrees warmer at night. This thermal buffering extends the growing season and protects the plant from freeze-thaw cycles that would damage less adapted species. The cushion also acts as a sediment trap, gradually accumulating fine particles and organic matter that enrich the immediate growing environment.
Common associates include other cushion plants like Raoulia eximia (vegetable sheep), Phyllachne colensoi , and Dracophyllum muscoides , as well as small herbs such as Gentianella bellidifolia and various Epilobium species. In slightly more sheltered sites, it may grow alongside tussock grasses like Chionochloa oreophila and small shrubs such as Hebe epacridea .
Plant Conservation
While Abrotanella caespitosa is not currently threatened and remains locally common in suitable habitat, it faces long-term challenges from climate change. As temperatures warm, the species may be forced to migrate to higher elevations, but in many locations, it already occupies mountain summits with nowhere higher to go. Studies suggest that cushion plants like this species are particularly vulnerable to increased competition from faster-growing plants that can invade as conditions become more favorable at higher elevations.
The species is also sensitive to physical disturbance. A single footstep can damage decades of growth, and recovery is extremely slow in the harsh alpine environment. Popular tramping routes through alpine areas have shown measurable impacts on cushion plant communities, with some damaged areas showing little recovery even after 20 years. This highlights the importance of staying on formed tracks and avoiding shortcuts across vegetated areas.
Research into the species' response to warming has revealed concerning trends. While cushion plants initially benefit from warmer conditions through increased growth rates, they simultaneously face increased competition from colonizing species. Additionally, changes in snow cover patterns - both reduced duration and altered timing - can expose plants to damaging freeze-thaw cycles during critical growth periods. Conservation efforts focus on monitoring population trends, protecting key habitats from recreational damage, and understanding the species' adaptive capacity to environmental change.
Growing Requirements
Soil Requirements
Use a very free-draining, gritty mix: coarse sand, fine gravel, and minimal organic matter. Alkaline to slightly acidic mineral substrates are suitable. Avoid water-retentive potting composts.
- Crevice or trough with rapid drainage
- Low-nutrient, mineral-rich medium
- Top dress with fine grit to protect the crown
Light Requirements
Needs high light and exposure. Full sun is best in cool climates; provide light afternoon shade in hotter districts to prevent heat stress.
- Full sun; strong airflow
- Shelter from stagnant, humid conditions
Water Requirements
Keep evenly moist during active growth but never waterlogged. Allow the surface to dry between light waterings. Winter wet combined with cold is the primary cultivation risk; ensure the crown stays airy and free of splash.
- Light, frequent watering in summer if dry
- Very sparing in winter; avoid saturated media
Planting Guide
Best Planting Practices
Plant into a prepared crevice or shallow trough with vertical stone faces to keep the crown dry. Tease roots gently across the crevice, backfill with a gritty mix, then top with 3-5 mm grit. Water to settle, then allow to almost dry. In humid, lowland sites, an alpine house or cold frame markedly improves success.
Ecological Role
Environmental Benefits
Cushion plants act as nurse structures, moderating temperatures at the surface and trapping fine sediments. Their microhabitats support tiny invertebrates and seedlings of other alpine herbs, enhancing local diversity in otherwise harsh terrain.
Uses & Significance
Garden Uses
Best for experienced rock gardeners. Excellent in crevice gardens, troughs, and raised scree beds in cool climates where drainage is impeccable.
- Alpine troughs and crevice plantings
- Textural contrast in rock gardens
- Specialist collections of alpine daisies
Ecological Value
Provides structure and microclimates in alpine habitats; cushions can trap moisture and wind-blown nutrients that benefit other small alpine species.
Landscaping Uses
Garden Design Applications
Excellent for rock gardens, alpine collections, and naturalistic plantings. Best used in open, well-drained positions where its distinctive form can be appreciated. Combines well with other native alpine plants and provides year-round structure. Consider placement carefully due to sharp foliage - avoid high-traffic areas. Creates dramatic focal points in contemporary and native-themed garden designs.
Seasonal Care
Spring
Resume light feeding; inspect for winter losses; repot troughs if needed.
Summer
Ensure airflow; water lightly during drought; protect from extreme heat spikes.
Autumn
Reduce watering as temperatures fall; tidy grit mulch; check drainage before winter.
Winter
Keep almost dry; avoid splash on the crown; ensure snowmelt drains rapidly.
Pruning
Pruning Techniques
As a slow-growing cushion plant, Abrotanella caespitosa requires minimal pruning. The primary maintenance task involves carefully removing any brown, dead, or rotting rosettes from within the cushion using fine tweezers to prevent fungal issues from spreading to healthy growth. If the plant spreads beyond its allocated space in a rock garden or trough, the outer edges can be gently trimmed back or lifted, though this is rarely necessary due to its moderate growth rate. In its natural habitat, it forms extensive mats, so allowing it to spread naturally highlights its best features.
How to Grow Cushion Daisy
From Seed
Propagation from seed offers the best method for producing multiple plants, though it requires patience and specific conditions. Seeds should be collected when the small flower heads turn fluffy (January-March) and sown immediately for best results, as viability decreases rapidly with storage. If storage is necessary, keep seeds in paper envelopes in a cool, dry place for no more than six months.
Prepare a seed tray with a mix of 50% fine sand, 30% perlite, and 20% sieved peat-free compost. Surface sow the tiny seeds, as they require light for germination. Cover with a thin layer of fine grit (1-2mm) to hold seeds in place while maintaining light penetration. Some growers report improved germination after a cold stratification period of 4-6 weeks at 2-4°C.
Maintain consistent moisture using bottom watering or fine misting. Germination typically occurs within 3-8 weeks at temperatures of 10-15°C. Seedlings develop extremely slowly - expect only 2-3mm of growth in the first year. Keep seedlings in their original containers for at least 18 months before attempting to transplant. Success rates average 40-60% from seed to established plant.
From Division
Division of established cushions is possible but challenging due to the woody rootstock and dense growth. This method is best attempted in early spring (September) when growth resumes. Select healthy cushions at least 10 centimeters across and 5 years old. Using a sharp, sterile knife, cut vertically through the cushion and rootstock, ensuring each division has both shoots and roots.
The woody nature of mature plants makes clean cuts difficult - some growers use a thin saw blade for larger specimens. Dust cut surfaces with fungicide to prevent rot. Plant divisions immediately into individual pots with extra-gritty alpine mix. Keep in a cool, shaded frame for 2-3 weeks, misting daily but avoiding water on the cushion surface. Success rates for division are typically 30-50%, significantly lower than seed propagation, making this method suitable only for special forms or when seed is unavailable.
From Cuttings
While rarely attempted, semi-ripe cuttings taken in late summer can root under optimal conditions. Select 1-2 centimeter shoots from the cushion edge, remove lower leaves, and insert into pure sand or perlite. Maintain high humidity without directly wetting the cuttings. Rooting, if successful, takes 3-4 months. This method has less than 20% success rate and is generally not recommended except for experimental purposes.
Advanced Techniques
Advanced propagation techniques include tissue culture for conservation purposes and specialized mycorrhizal inoculation to improve establishment success. Research into optimal hormone treatments and environmental triggers continues to improve propagation rates. Commercial nurseries are developing improved protocols for mass production while maintaining genetic diversity. Understanding these methods helps both commercial growers and dedicated enthusiasts achieve better results with challenging species.
Troubleshooting Common Issues
Poor germination often results from old seed or inadequate stratification. Seedling losses typically indicate overwatering or insufficient drainage. Slow establishment may suggest inappropriate soil conditions or excessive heat stress. Yellowing foliage usually indicates nutrient deficiency or waterlogged conditions. Regular monitoring and prompt intervention prevent minor issues from becoming major problems affecting long-term plant health and garden performance.
Pests & Diseases
Few pests in alpine settings. In cultivation, crown rot from stagnant moisture is the main issue; ensure perfect drainage and strong airflow. Slugs and snails may browse soft new growth in damp periods.
Cultural Significance
Traditional Uses and Values
Cushion Daisy represents the remarkable adaptation of New Zealand's alpine flora to extreme environments. While not specifically used by Māori due to its remote high-altitude habitat, these cushion plants embody the resilience and specialized evolution found throughout New Zealand's mountain ecosystems. They serve as indicators of pristine alpine environments and are valued by botanists and conservationists as examples of unique island biogeography. For modern New Zealanders, these plants symbolize the fragile beauty of our alpine heritage and the importance of protecting high-country ecosystems from climate change and human impact.
Bonus Tip
Unusually for an alpine cushion, Abrotanella caespitosa often grows in bogs and permanently wet hollows in the wild. This makes it more tolerant of moisture than many dry-scree alpines, though in lowland cultivation, sharp drainage is still recommended to prevent stagnation and mimic the oxygenated flow of mountain water.
