Sand Gunnera

Botanical name: Gunnera dentata
Synonyms: None
Common name(s): Sand gunnera

About:
A small, creeping perennial herb endemic to New Zealand, forming low mats of grey-green, coarsely toothed leaves. Despite belonging to the same genus as the enormous ornamental gunneras, Gunnera dentata is a diminutive ground-hugging species adapted to damp, exposed habitats. Its relatively stout stolons creep through sand, soil and other substrates, allowing colonies to spread laterally. Male and female flowers occur on separate plants, with female plants producing conspicuous yellow, orange to reddish fruits held above the foliage.

Natural habitat:
Occurs from lowland to subalpine environments in damp to wet open habitats. It is particularly associated with moist sandy ground, wet depressions, turf, seepages and other periodically or permanently damp sites. Its creeping stolons are well adapted to growing through loose sandy substrates.

Growing environment:
Frost, Sun, Wind, Damp & Wet conditions tolerant. Prefers consistently moist ground and is particularly suited to open sites where the soil does not completely dry out. It can tolerate exposed conditions and cool climates.

Endemic distribution:
Endemic to New Zealand.

Height:
Approximately 2–10 cm tall, with flowering and fruiting stems extending above the foliage.

Width:
Individual stolons may extend to approximately 40 cm, with established plants spreading into larger interconnected patches.

Flowering:
December – February
Produces small, inconspicuous greenish flowers on short inflorescences. Plants are dioecious, with male and female flowers occurring on separate plants.

Fruiting:
December – February
Female plants produce distinctive fleshy, elongated pear-shaped to obconical drupes. These are initially pale yellow and mature through orange to reddish shades, making fruiting plants considerably more conspicuous than flowering specimens.

Uses:
• Native ground cover
• Wetland and damp-site restoration
• Alpine and subalpine gardens
• Bog and wetland gardens
• Damp rock gardens
• Native turf planting
• Wildlife and biodiversity planting

Appearance:
Growth habit:
A low-growing, stoloniferous perennial herb forming spreading patches. The relatively stout, branched stolons usually creep along or just beneath the substrate and may extend to around 40 cm.

Leaves:
Leaves are small, generally about 1–4 cm long, although occasionally larger. The blades are usually ovate to elliptic but may be orbicular, obovate or somewhat rhomboid. They are relatively firm to slightly leathery, green to grey-green and glabrous to sparsely hairy. Margins are characteristically coarse and irregularly crenate or serrate, giving the foliage its distinctly toothed appearance. Leaves are carried on stout, somewhat flattened petioles.

Flowers:
Flowers are very small and greenish, arranged along short inflorescences. Male flowers have two small petals, while female flowers develop prominent slender styles. Their small size makes flowering relatively inconspicuous.

Fruit:
The fleshy drupes are approximately 3–6 mm long and range from pale yellow through deep orange to reddish when mature. They are elongated, pear-shaped to obconical and spaced along exposed fruiting stalks that usually rise above the leaves.

Ecology:
Gunnera dentata is primarily associated with moist and wet environments and is classified as a facultative wetland species, meaning it usually behaves as a hydrophyte but can occasionally occur outside wetlands.

Its creeping stolons enable it to colonise suitable open ground and form persistent low vegetation in habitats subject to exposure and disturbance. The fleshy fruits are dispersed principally by animals that consume them, while ants may also contribute to dispersal.

Like other Gunnera, the species belongs to a remarkable plant lineage known for associations with nitrogen-fixing cyanobacteria, an adaptation that can assist plants growing in nutrient-poor environments.

Associated habitats:
Wetland margins, damp sand, coastal and inland turf, seepages, moist depressions, boggy ground, stream margins, wet grassland and damp montane to subalpine vegetation.

How to grow:
Best grown in a cool, open position with consistently moist soil. Full sun is suitable where adequate moisture is maintained, while some light shade can help prevent excessive drying in warmer environments.

A moisture-retentive but aerated substrate is preferable. It is particularly well suited to bog gardens, wetland margins, damp rockeries and low native ground-cover plantings. Avoid allowing established plants to dry out for extended periods.

Because plants spread naturally by stolons, they can gradually form attractive low mats when conditions are suitable. Both male and female plants are required if fruit production is desired.

Propagation:
Can be propagated vegetatively by carefully separating rooted sections of stolon and replanting them immediately into consistently moist substrate. This is likely to be the simplest method for maintaining selected plants.

Propagation from fresh seed is also possible. Ripe fruits should be collected from female plants, with the fleshy material removed before sowing. Maintain consistently moist conditions during establishment.

Cultural use:
No well-documented traditional Māori uses specific to Gunnera dentata are known.

Garden value:
An unusual and attractive native ground cover for gardeners with naturally damp sites. Its small grey-green toothed leaves form neat creeping patches, but the greatest ornamental interest comes from female plants when their yellow, orange to reddish fruits are displayed above the foliage.

Its combination of low growth, cold tolerance and preference for damp ground makes it particularly useful for native wetland gardens, alpine collections, damp rockeries and naturalistic plantings where many conventional ground covers struggle.