Alpine Kelleria

Botanical name: Kelleria dieffenbachii
Synonyms: Drapetes dieffenbachii, Drapetes macrantha
Common name(s): Alpine Kelleria

About:
A tiny, mat-forming alpine subshrub that spreads across exposed mountain ground in dense to relatively loose patches. Its slender woody stems creep along the surface and root as they spread, producing numerous short branchlets clothed in minute, tough leaves.

Despite its diminutive size, Kelleria dieffenbachii is a true woody perennial remarkably adapted to harsh alpine conditions. Its tiny white flowers are produced in small terminal clusters and contrast attractively with the tightly packed green foliage.

It is indigenous to New Zealand but not endemic, also occurring in Australia, Tasmania and the highlands of New Guinea.

Natural habitat:
Montane to alpine and subalpine environments.

Occurs in exposed alpine vegetation including fellfield and feldmark, open tussock grassland, gravelly ground, rocky slopes, forest and scrub margins and other sparsely vegetated mountain habitats.

It generally favours open, well-drained sites and appears particularly characteristic of comparatively dry alpine ground, although it has occasionally been recorded from Sphagnum peatland.

Growing environment:
Full Sun, Partial Shade, Frost, Snow, Wind, Alpine Exposure, Free-draining Soil, Gravel & Rocky Soil tolerant.

Best suited to cool, open positions with excellent drainage. It is naturally adapted to severe alpine conditions but can be more difficult to maintain in warm, humid lowland environments.

Endemic distribution:
Indigenous but not endemic to New Zealand.

Occurs in montane, subalpine and alpine areas of the North Island and South Island and on Stewart Island/Rakiura. Reports also exist from some offshore island groups, although aspects of its wider distribution have historically been complicated by variation within the Kelleria group.

Outside New Zealand it occurs in south-eastern Australia including Tasmania and in high-elevation habitats of New Guinea.

Height:
Approximately 2–5 cm, occasionally slightly taller where branchlets become ascending.

Width:
Individual patches commonly reach approximately 25 cm across and may become larger as the creeping stems continue to root and spread.

Flowering:
Primarily spring–summer, with flowering records extending over a broader season in some areas.

Tiny white flowers occur in compact heads, generally with 3–8 flowers in each cluster.

The perianth tube is approximately 1.5–2.5 mm long and ranges from sparsely to densely hairy. The broad ovate-oblong lobes are approximately 1.5–2 mm long.

Fruiting:
Produces minute ovoid fruits approximately 1.5 mm long.

The small achenes are thought to be capable of wind dispersal, although other dispersal mechanisms may also contribute.

Uses:
• Alpine rock gardens
• Native rockeries
• Crevice gardens
• Gravel gardens
• Alpine troughs
• Specialist native collections
• Mat-forming groundcover
• Alpine restoration
• Botanical collections
• Naturalistic mountain plantings

Its extremely low growth and fine foliage make it particularly attractive among rocks, gravel and other small alpine plants.

Appearance:
Growth habit:
A diminutive woody perennial subshrub forming dense to loose, carpet-like patches.

The main stems and branches are prostrate, up to approximately 3 mm in diameter, and characteristically produce roots where they contact suitable substrate.

Numerous short branchlets arise close together. These are prostrate to ascending, become largely hairless with age and reach approximately 5 cm long.

This combination of creeping stems and adventitious rooting enables established plants to form persistent mats over exposed alpine ground.

Leaves:
Leaves are extremely small, approximately 2.5–3.5 mm long and 0.5–1 mm wide at the base.

They are tough and leathery, erect to closely appressed against the stems and sometimes slightly incurved. Each leaf tapers from its broader base toward a blunt apex.

The leaves are strongly concave-convex, with veins varying from conspicuous to obscure. Their margins bear fine hairs, while the tip has a distinctive dense tuft of hairs.

Flowers:
Tiny white flowers are clustered into heads containing approximately 3–8 flowers.

Four surrounding scales are present, sometimes divided or arranged into closely grouped pairs.

The perianth tube is approximately 1.5–2.5 mm long and may be sparsely or densely covered with fine hairs. The lobes are approximately 1.5–2 mm long, broadly ovate to ovate-oblong and similarly variable in hairiness.

Although individually minute, the flowers can become conspicuous when numerous plants bloom simultaneously across a compact mat.

Fruit:
The ovary is ovoid with a tufted apex and develops into an equally tiny ovoid fruit approximately 1.5 mm long.

Its small size potentially assists dispersal across exposed alpine terrain.

Ecology:
Kelleria dieffenbachii is specialised for exposed montane and alpine environments where plants experience strong winds, intense sunlight, frost, snow and short growing seasons.

Its prostrate habit keeps most growth close to the ground, reducing exposure to damaging winds. Small, tough leaves help limit moisture loss, while creeping stems capable of rooting at their nodes allow the plant to gradually occupy stable patches between stones and other low vegetation.

It forms part of diverse alpine communities and may grow alongside tussocks, dwarf shrubs, cushion plants and other low-growing herbs.

Variation occurs between populations, with differences reported in growth habit, colour and degree of stem and leaf hairiness.

Associated habitats:
Alpine fellfield, feldmark, rocky slopes, gravel terraces, scree margins, alpine grassland, Chionochloa tussockland, subalpine shrubland, open mountain vegetation, forest margins and occasionally Sphagnum peatlands.

Associated vegetation may include species of Chionochloa, Dracophyllum, Olearia and other dwarf alpine shrubs and herbs. It can also occur alongside Kelleria villosa.

How to grow:
Grow in a cool, open position in full sun or light partial shade.

Excellent drainage is important. A gritty, mineral-rich substrate containing fine gravel, coarse sand or pumice is preferable to rich, moisture-retentive garden soil.

Rock gardens, raised alpine beds and troughs are particularly suitable because they allow good drainage around the plant’s small root system while keeping competition from vigorous plants to a minimum.

Provide regular moisture during establishment but avoid prolonged waterlogging. Once established, plants should be allowed to form their natural creeping mats with minimal disturbance.

In warmer lowland districts, a cool root zone and protection from excessive summer heat may be more important than protection from cold.

Propagation:
Can be propagated from seed or by division of established mats.

Fresh seed can be sown into a fine, free-draining alpine propagation mix. Cool conditions are preferable, and cold stratification may assist germination.

Vegetative propagation is possible because the creeping stems naturally produce roots. Carefully separate well-rooted portions of an established mat and transplant them into a gritty medium.

Keep newly divided plants consistently moist but never waterlogged until established.

Cultural use:
There is no well-documented traditional Māori use specifically recorded for Kelleria dieffenbachii.

The species does, however, form part of the distinctive indigenous flora of New Zealand’s montane and alpine ecosystems.

The botanical name commemorates Ernst Dieffenbach, the 19th-century German naturalist who collected the plant during his exploration of New Zealand, including his historic ascent of Taranaki Maunga in 1839.

Garden value:
An excellent specialist native for alpine gardens, troughs and rockeries where its minute scale can be appreciated.

Its dense carpeting growth, tiny sculptured leaves and delicate white flowers provide considerable interest when planted among rocks, gravel and other dwarf native alpines.

Unlike vigorous conventional groundcovers, Kelleria dieffenbachii is best positioned where it will not be overwhelmed by taller or faster-growing plants.

For gardeners able to provide cool conditions and sharp drainage, it offers an attractive way of representing New Zealand’s remarkable high-country flora on a very small scale.