Trailing Pennywort

Botanical name: Hydrocotyle elongata
Synonyms: None
Common name(s): Trailing pennywort

About:
A low-growing perennial groundcover endemic to New Zealand, Hydrocotyle elongata forms spreading patches of soft green foliage on slender creeping stems. Its leaves are rounded but deeply divided into usually five broad segments, with each segment further lobed and serrated, giving the foliage a distinctive irregular, almost parsley-like appearance.

The leaves and petioles are noticeably hairy, and many of the marginal teeth end in conspicuous hair tips. Small, inconspicuous flowers are carried in simple umbels on long stalks that rise well above the leaves.

Natural habitat:
Found in damp open ground, forest margins, stream banks, grassland edges and other moist low-growing vegetation.

It commonly occupies sites where low vegetation and consistent moisture allow its creeping stems to spread into broad patches.

Growing environment:
Frost, Sun, Partial Shade, Damp Soil & Free Draining tolerant. Best in moist soils with good organic content, but capable of tolerating a range of light levels provided adequate moisture is available.

Endemic distribution:
Endemic to New Zealand.

Occurs naturally in the North and South Islands.

Height:
Approximately 5–10 cm tall.

Width:
Spreading indefinitely by creeping stems and capable of forming extensive patches.

Flowering:
November – March
Produces numerous small flowers in simple umbels borne on slender peduncles extending well above the foliage.

Fruiting:
December – April
Produces small hairy fruits approximately 1.5–1.8 mm long.

Uses:
• Native groundcover
• Woodland and forest-floor planting
• Damp banks
• Stream-margin planting
• Underplanting beneath shrubs and trees
• Naturalistic native gardens
• Soil cover and erosion reduction
• Filling gaps between larger native plants

Appearance:
Growth habit:
A perennial creeping herb forming broad, low patches.

The stems are slender and spread across the soil surface, allowing colonies to expand gradually through suitable habitat.

Leaves:
Leaves are generally 5–35 mm across, most commonly around 10–25 mm.

The blade is dull green and moderately hairy on both surfaces, and is usually divided into five broad segments for approximately one-quarter to two-thirds of the distance toward the centre.

Each segment is broad-oblong to obovate and is usually divided again into three lobes with serrated margins.

Many of the marginal teeth terminate in conspicuous hairs, producing an irregular outline.

The leaf stalks are densely hairy.

Flowers:
The flowers are very small and visually inconspicuous.

They are arranged in simple umbels containing numerous flowers, carried on slender peduncles considerably taller than the surrounding foliage.

Individual flowers are borne on relatively long pedicels.

Fruit:
The fruit is small, hairy and approximately 1.5–1.8 mm long by 1–1.5 mm wide.

It has a distinctly acute dorsal edge and slender raised ribs.

The mericarps are dispersed by wind and water.

Ecology:
Hydrocotyle elongata contributes to the dense ground layer of damp native vegetation.

Its spreading stems help maintain ground cover, reduce exposed soil and provide shelter for small invertebrates and other organisms close to the soil surface.

The small fruits can be transported by both flowing water and wind, allowing the species to colonise suitable damp sites downstream or across disturbed ground.

Its mat-forming habit makes it particularly effective in filling gaps in low vegetation.

Associated habitats:
Damp forest floors, forest margins, stream banks, grassland margins, shaded banks, moist disturbed ground and other low-growing vegetation.

How to grow:
Best grown in moist, humus-rich soil in partial shade or filtered light, although it will tolerate full sun where soil moisture remains reliable.

Plant small rooted sections directly into prepared ground and keep consistently moist while establishing.

Once established it spreads readily and may be trimmed where necessary to keep it within defined areas.

It is well suited to woodland gardens, beneath larger native shrubs and alongside streams or damp pathways.

Propagation:
Easily propagated by division of established patches.

Lift rooted sections of creeping stem and replant directly into moist soil, ensuring each division has a healthy section of root and foliage.

Propagation from seed is also possible using fresh ripe seed, which should be sown onto a moist, fine propagation medium and kept evenly damp.

Cultural use:
No specific traditional Māori use is widely documented for Hydrocotyle elongata.

Its primary significance is ecological as a characteristic endemic component of New Zealand’s damp ground-layer vegetation.

Garden value:
A useful native groundcover for moist and shaded gardens.

The finely divided, softly hairy foliage provides a delicate texture beneath larger plants and contrasts well with ferns, sedges and broader-leaved forest species.

Its ability to spread into a continuous low carpet makes it particularly valuable for naturalistic planting, stream margins and difficult shaded areas where a small native groundcover is required.