Dieffenbach’s Speargrass

Botanical name: Aciphylla dieffenbachii

Common name(s): Dieffenbach’s Speargrass, Soft Speargrass, Coxella

Plant facts:

A distinctive Chatham Islands speargrass with soft, drooping blue-green foliage and large golden flower spikes. Unlike many speargrasses, this species has flexible, less rigid leaves and is highly adapted to cool coastal environments.

Natural habitat:

Strictly coastal, growing on cliffs, rocky scarps, coastal slopes, and petrel-burrowed ground. Often associated with basalt coastal substrates.

Growing environment:

Coastal, Wind, Sun & Free draining tolerant.

Endemic distribution:

Endemic to the Chatham Islands, including Chatham, Pitt, Mangere, Little Mangere, Rangatira, and surrounding offshore islands.

Height:

Foliage up to 70 cm long, flowering stems reaching around 1 m tall

Flowering:

November – February
Produces dense golden-yellow flower clusters on stout upright stems.

Fruiting:

January – June
Large winged fruits mature from golden-yellow to pale brown-grey.

Uses:

• Coastal specimen planting
• Chatham Islands restoration projects
• Architectural foliage plant
• Habitat plant for native insects

Appearance:

Growth habit:
A tufted perennial with a very thick taproot and spreading clumps of soft foliage.

Leaves:
Leaves are glaucous blue-green, soft, and drooping rather than rigid. The leaflets are narrow with blunt tips and arranged in several pairs along the leaf stem.

Flowers:
Large upright flower spikes carry dense clusters of golden-yellow flowers. Male and female flowers occur on separate plants.

Sap:
When damaged, the plant exudes a sticky white latex.

Fruit:
Produces large flattened winged fruits that split into two sections when mature.

How to grow:

Easy to grow from fresh seed, though seed viability is short-lived. Best grown in full sun with fertile, free-draining soil that retains some moisture. Particularly suited to cool coastal gardens. Dislikes humidity and prolonged dryness, and may die after heavy flowering.