Chatham Island Ice Plant

Botanical name: Disphyma papillatum
Synonyms: None
Common name(s): Chatham Island Ice Plant

About:
Disphyma papillatum is a beautiful, mat-forming succulent endemic to the Chatham Islands. Closely related to horokaka (Disphyma australe), it is distinguished by its flattened, two-angled stems and tiny papillae (raised bumps) covering its stems, leaf margins and seeds. It thrives in some of New Zealand’s most exposed coastal environments, where its vibrant flowers and creeping habit help stabilise rocky shorelines.

Natural habitat:
Grows abundantly on exposed coastal cliffs, rocky outcrops, gravel and cobble beaches, coastal headlands and around seabird nesting sites, including petrel burrows. It is well adapted to harsh, windswept coastal conditions.

Growing environment:
Prefers full sun and well-drained soils with moderate moisture. Highly tolerant of coastal exposure, salt spray and poor soils, making it ideal for difficult seaside gardens.

Endemic distribution:
Endemic to the Chatham Islands, including Rekohu (Chatham Island), Rangiauria (Pitt Island), Rangatira (South East Island), Mangere, Little Mangere, Rabbit Island, Castle Island, Forty Fours, Star Keys, Sisters Islands and Western Reef.

Height:
5–15 cm

Width:
Spreads up to 1 m or more

Flowering:
July–May, with the main flowering display occurring during spring and summer.

Fruiting:
Present throughout the year.

Uses:
• Coastal groundcover
• Rock gardens
• Cliff and bank stabilisation
• Container planting
• Coastal restoration
• Specialist native plant collections

Appearance:
Growth habit:
A low-growing, trailing succulent that spreads by creeping stems which root freely at the nodes, gradually forming dense mats.

Stems:
Distinctively flattened and two-angled rather than rounded, smooth to the touch but covered with tiny raised papillae that give the plant its scientific name.

Leaves:
Fleshy, triangular leaves 4–30 mm long with pointed tips and papillate margins. Leaves are opposite and joined at their bases around the stem.

Flowers:
Showy daisy-like flowers 20–40 mm across with numerous narrow petals arranged in three to five rows. Flower colour ranges from white and pale pink through to rich pink, purple and occasionally deep bluish-purple, surrounding a bright yellow centre.

Fruit:
Small fleshy capsules containing numerous tiny yellowish-brown seeds with a distinctly papillate surface. The capsules open in wet conditions to release the seeds.

Ecology:
This species is an important pioneer plant of the Chatham Islands’ coastal ecosystems. It stabilises shallow soils on exposed cliffs and beaches while providing nectar and pollen for native insects. The fleshy fruits may be dispersed by birds, while seeds can also be spread by wind and seawater.

Associated habitats:
Coastal cliffs, rock stacks, gravel and cobble beaches, exposed headlands, petrel colonies, coastal herbfields and open coastal forest margins.

How to grow:
Grow in full sun in free-draining soil. Although naturally occurring on nutrient-poor coasts, it performs well in fertile garden soils provided drainage is excellent. Water during establishment, then only occasionally during extended dry periods inland.

Propagation:
Very easily propagated from rooted stem cuttings or fresh seed. Stem sections root readily when placed on sandy or gritty soil, making this one of the easiest coastal succulents to propagate.

Cultural use:
Although no specific traditional Māori uses have been widely recorded for this Chatham Islands endemic, it forms an important part of the indigenous coastal flora and contributes significantly to the unique botanical identity of Rekohu and the surrounding islands.

Garden value:
An outstanding ornamental groundcover for coastal gardens, rockeries and containers. Its colourful flowers, compact succulent foliage and exceptional tolerance of wind and salt spray make it an excellent choice for exposed seaside landscapes, while its rarity outside the Chatham Islands adds considerable botanical interest.