Creeping Gunnera

Botanical name: Gunnera prorepens
Synonyms: Gunnera flavida
Common name(s): Creeping gunnera

About:
A distinctive creeping perennial herb endemic to New Zealand, recognised by its relatively large, thin, almost entire leaves and conspicuous raspberry-like clusters of fleshy fruit. Gunnera prorepens is strongly associated with wet habitats and is classified as an obligate wetland species. It spreads through moist ground to form low colonies and is especially attractive when fruiting. Both red-purple and yellow-fruited forms occur naturally, sometimes growing together within the same population.

Natural habitat:
Found in coastal and inland wet environments from lowland to subalpine elevations. Typical habitats include permanently wet ground, seepages, stream margins, swampy sites, wet grasslands, bog margins and other saturated open habitats.

Growing environment:
Wet, Damp, Frost, Sun & Partial Shade tolerant. Requires consistently moist to saturated soil and performs best where the substrate never dries out for prolonged periods.

Endemic distribution:
Endemic to New Zealand. Occurs in the North Island from approximately Auckland southwards, throughout the South Island, and on Stewart Island/Rakiura.

Height:
Generally approximately 5–20 cm tall, with the leaves and fruiting spikes rising above the creeping stems.

Width:
Spreads by creeping growth to form extensive low colonies where moisture remains suitable.

Flowering:
September – January
Produces small, inconspicuous flowers. Plants are dioecious, with male and female flowers occurring on separate individuals.

Fruiting:
November – March
Female plants develop conspicuous fleshy fruiting heads held above the foliage. The drupes are usually densely packed and may be red-purple, bright red or yellow.

Uses:
• Wetland restoration
• Stream and seepage planting
• Bog gardens
• Damp native ground cover
• Subalpine and alpine collections
• Native biodiversity planting
• Specialist botanical gardens

Appearance:
Growth habit:
A low-growing, creeping perennial herb that spreads through persistently wet substrates. Established plants form loose to dense patches and can gradually colonise suitable open wet ground.

Leaves:
Leaves are comparatively large for a native Gunnera, approximately 2.5–14 cm long. The blades are ovate and usually shallowly heart-shaped at the base. Unlike several related species, the leaves are not lobed and have only shallowly crenate margins or may appear almost entire. They are thin and membranous rather than strongly leathery, and are usually more or less hairless.

Flowers:
Flowers are very small and visually inconspicuous. Male and female flowers occur on separate plants, meaning both sexes need to be present within pollinating distance for natural fruit production.

Fruit:
The fruit is the species’ most distinctive feature. Numerous small fleshy drupes are usually crowded together into dense, upright fruiting heads resembling miniature raspberries. Individual fruits are shortly obconical to rounded and range from red-purple and red to yellow.

The different fruit colours represent naturally occurring colour forms rather than separate species. The yellow-fruited form was historically described as Gunnera flavida.

Ecology:
Gunnera prorepens is strongly dependent on wet environments and is classified as an obligate wetland species, meaning it almost always occurs as a hydrophyte.

Its low creeping growth helps stabilise wet soil and allows it to occupy gaps amongst sedges, mosses and other low wetland vegetation. The exposed fleshy fruiting heads are adapted for dispersal by animals that consume the drupes, while ants may also contribute to movement of the seeds.

As with other members of Gunnera, the plant forms an unusual symbiotic relationship with nitrogen-fixing Nostoc cyanobacteria. This allows the plant to supplement its nitrogen supply and can be advantageous in nutrient-poor wetland soils.

Gunnera prorepens also hybridises naturally with Gunnera monoica where the two species grow together. These hybrids have historically been called Gunnera mixta and may show intermediate foliage and orange-coloured fruits.

Associated habitats:
Wet grassland, swamp margins, bogs, seepages, streambanks, wet depressions, coastal wetlands, saturated turf, subalpine wetlands and other permanently moist sites.

How to grow:
Best grown in permanently moist to wet soil. It is particularly suitable for pond margins, seepages, bog gardens and naturally wet parts of the garden where ordinary ground covers struggle.

Full sun is suitable in cool climates provided the soil remains continuously damp. Partial shade can help maintain moisture in warmer conditions. Humus-rich, peaty or organically enriched soils are suitable, but the key requirement is reliable water.

Avoid planting in locations that dry completely during summer. Competition from vigorous weeds should also be controlled, particularly while plants are establishing.

Because the species is dioecious, both male and female plants are required if fruiting is desired.

Propagation:
Can be propagated vegetatively from rooted creeping sections or by division of established plants. Rooted pieces should be replanted promptly into saturated or consistently moist substrate.

Fresh seed may also be used. Collect ripe fruit from female plants, remove the fleshy coating and sow into a moist, fine-textured medium. Maintain constant moisture throughout germination and establishment.

Cultural use:
No well-documented traditional Māori uses specific to Gunnera prorepens are established in the available botanical information.

Garden value:
One of the more ornamental New Zealand Gunnera species, particularly when female plants are covered in dense raspberry-like fruiting heads. The contrast between the broad, soft green foliage and bright red, purple-red or yellow fruit makes it especially effective in wetland and bog gardens.

Its naturally creeping habit also makes it useful as a low native ground cover around ponds, streams and permanently damp garden areas. Unlike the giant exotic gunneras, it remains compact and is well suited to smaller-scale native plantings.