Coastal Tussock

Botanical name: Chionochloa bromoides
Synonyms: Danthonia bromoides
Common name(s): Coastal Tussock, Seabird Tussock

About:
A distinctive coastal snow tussock endemic to northern New Zealand offshore islands and headlands. It forms bright green, often sprawling tussocks with long arching leaves and dense bristly flower heads. This species is strongly associated with seabird colonies, where it often grows among burrows on exposed coastal cliffs and rocky slopes.

Natural habitat:
Coastal cliffs, bluffs, rocky headlands, offshore islands, rock stacks and seabird scrub, particularly in areas occupied by petrels and other burrowing seabirds.

Growing environment:
Prefers full sun, excellent drainage and open coastal conditions. Tolerates strong winds, salt spray and drought once established. Best suited to cool coastal gardens and rocky sites with minimal competition from larger plants.

Endemic distribution:
Endemic to New Zealand. Mainly confined to northern offshore islands and coastal headlands from the Bay of Islands south to the Poor Knights, Chicken and Mokohinau Islands, with an outlying population at Maunganui Bluff.

Height:
500–700 mm

Width:
Up to 1 m across

Flowering:
September–December

Fruiting:
November–March

Uses:
• Coastal restoration planting
• Seabird habitat restoration
• Coastal gardens
• Native grassland plantings
• Erosion control on coastal slopes
• Specialist native plant collections

Appearance:

Growth habit:
A stout, bright green tussock with arching to sprawling foliage. Older plants often develop a cascading form, particularly on cliffs and steep slopes.

Leaves:
Leaves up to 500 mm long and 10 mm wide, bright green, flat to shallowly U-shaped and smooth. Sheaths are shiny yellow and persistent, becoming fibrous with age. Leaf bases and sheath margins are fringed with long hairs.

Flowers:
Produces compact, congested flower heads up to 200 mm long. The flowering stems carry dense clusters of awned spikelets, giving the inflorescence a bristly appearance.

Fruit:
Small wind-dispersed grass seeds develop within the densely packed flower heads and are released during late summer.

Ecology:
Closely associated with coastal seabird colonies, particularly petrels. Mature plants often have their bases extensively burrowed by nesting seabirds. Seeds are dispersed by wind and tussocks help stabilise fragile coastal soils.

Associated habitats:
Coastal cliffs, rocky bluffs, offshore islands, petrel scrub, exposed headlands, rock stacks and maritime grasslands.

How to grow:
Plant in full sun in a free-draining site with good air movement. Suitable for coastal gardens, rocky banks and cliff-top plantings. Avoid excessive root disturbance after planting.

Propagation:
Best grown from fresh seed. Young plants establish slowly and should be planted into their permanent position early, as mature plants dislike being moved.

Cultural use:
An important component of northern New Zealand’s offshore island ecosystems and closely linked with the ecology of seabird colonies.

Garden value:
A striking coastal tussock valued for its bright green foliage, cascading growth habit and strong architectural form. Excellent for coastal landscapes, native grass plantings and restoration projects.