Chatham Island Geranium

Botanical name: Geranium traversii
Synonyms: Geranium traversii var. elegans
Common name(s): Chatham Island Geranium

About:
A distinctive, low-growing perennial geranium endemic to the Chatham Islands. Geranium traversii forms broad patches of attractive silvery-grey to grey-green foliage and produces comparatively large white, pink or occasionally pale purple flowers. Its combination of softly hairy foliage, colourful flowers and naturally compact habit makes it one of the most ornamental of New Zealand’s native geraniums and an excellent species for coastal, rock and native gardens.

Natural habitat:
A predominantly coastal species occurring on cliffs, consolidated and mobile sand dunes, limestone rocks and cliffs, steep peat-filled crevices, rocky crevices and erosion hollows. It is adapted to exposed maritime environments where plants experience strong winds, salt-laden air and relatively free-draining substrates.

Growing environment:
Sun, wind, coastal exposure and free-draining tolerant. Best grown in full sun with good air circulation and well-drained soil. It is adaptable in cultivation but dislikes excessive or persistent moisture around its rootstock.

Endemic distribution:
Endemic to the Chatham Islands group, where it occurs naturally on Chatham Island, Pitt Island and many of the surrounding vegetated islands, islets and rock stacks.

Height:
Approximately 15–30 cm tall.

Width:
Forms spreading patches up to approximately 60–80 cm across.

Flowering:
Can flower throughout the year, with the main display occurring during spring and summer. Flowers are usually pink or white, occasionally pale purple, and approximately 20–25 mm across, sometimes reaching 30 mm.

Fruiting:
Can fruit throughout the year. The elongated fruits develop the characteristic beaked form typical of native geraniums, eventually releasing dark brown to almost black seeds.

Uses:
• Native groundcover
• Coastal gardens
• Rock and gravel gardens
• Banks and exposed slopes
• Container planting
• Flowering borders
• Chatham Islands-themed plantings
• Specialist native plant collections
• Pollinator-friendly planting

Appearance:
Growth habit:
A leafy, rosette-forming perennial developing a stout, deeply descending and woody-based rootstock. Mature plants branch near ground level and may produce stolons, gradually forming substantial low patches. Old petiole and stipule remains persist around the base, giving established plants a robust appearance.

Leaves:
Leaves are particularly attractive and are usually densely covered in fine silvery hairs, giving the plant its characteristic silvery-grey to grey-green appearance. Basal leaves are carried on slender stalks that can reach approximately 220 mm long. The rounded to kidney-shaped leaf blades range from about 15–100 mm across and are divided into 5–7, occasionally 8, broad lobes. These lobes may be further toothed or divided. Some naturally occurring plants develop attractive purple-toned foliage.

Flowers:
Flowers are borne singly on slender stalks above the foliage and are unusually large for a New Zealand native geranium, generally 20–25 mm and occasionally up to 30 mm across. The broad petals range from white through various shades of pink to occasional pale purple. Flowers commonly display several darker longitudinal veins, adding considerable detail to the petals.

Fruit:
Following flowering, elongated beaked fruits develop. The individual mericarps are covered in silky hairs and contain dark brown, reddish-brown, purple-brown or almost black seeds. When mature, the specialised fruit structure assists in dispersing the seeds away from the parent plant.

Ecology:
Geranium traversii is strongly adapted to the exposed maritime conditions of the Chatham Islands. Its low growth, substantial rootstock and densely hairy foliage help it withstand wind, salt exposure and the relatively harsh conditions of coastal cliffs and dunes.

The flowers provide a seasonal resource for visiting insects, while its spreading growth helps occupy exposed ground and stabilise small areas of loose or disturbed substrate.

Although the species remains secure overall, some populations on the larger Chatham Islands have declined through habitat modification and competition from invasive plants, particularly marram grass in coastal dune habitats.

Associated habitats:
Coastal cliffs, mobile and consolidated sand dunes, limestone outcrops, rocky coastal slopes, peat-filled crevices, rock fissures and erosion hollows.

It is characteristic of the open, windswept coastal vegetation of the Chatham Islands and is particularly well adapted to sites where taller vegetation is restricted by exposure.

How to grow:
An unusually accommodating Chatham Islands endemic that can be grown successfully through much of New Zealand. Plant in full sun for the densest growth, best foliage colour and strongest flowering.

Good drainage is important. It performs well in sandy, gravelly or ordinary garden soils provided they do not remain persistently waterlogged. Once established, plants tolerate considerable coastal exposure and wind.

Avoid overly wet, humid or heavily shaded positions. Removing old flower stalks and tired foliage can help maintain a compact appearance, although otherwise very little pruning is required.

Its relatively compact size also makes it an excellent container plant, particularly where its silver foliage and colourful flowers can be viewed closely.

Propagation:
Easily propagated from fresh seed. Mature seed should be collected as the fruits ripen and sown into a free-draining seed-raising medium.

Plants can also be propagated vegetatively where preservation of a particular flower or foliage colour is desirable. This is especially useful for maintaining selected forms with particularly silver, purple-toned or unusually coloured foliage and flowers.

Cultural use:
No specific traditional Māori or Moriori uses for Geranium traversii are widely documented. Its significance today lies particularly in its status as a distinctive component of the endemic Chatham Islands flora and as one of the more readily cultivated plants from that island group.

Garden value:
An outstanding native groundcover combining attractive foliage with a long flowering period. The soft silver-grey leaves contrast beautifully with its white, pink and occasionally pale purple flowers, making it suitable for both naturalistic native planting and more formal ornamental gardens.

It is especially valuable for exposed coastal gardens, rockeries, banks and containers. Unlike many geographically restricted island endemics, Geranium traversii adapts readily to cultivation and can be successfully grown across a wide range of New Zealand conditions, provided drainage is adequate.