Cutty Grass
Botanical name: Gahnia lacera
Synonyms: Lampocarya lacera
Common name(s): Cutty Grass, Tarangarara, Toetoe Kiwi
About:
Cutty Grass is a robust native sedge forming dense yellow-green tussocks with distinctive bamboo-like stems. It is easily recognised by its hard creeping rhizomes, sharply edged foliage and tall, rigid flower panicles carrying glossy black seeds.
Although difficult to establish in cultivation, mature plants are hardy and adaptable. Their strong architectural form makes them valuable for naturalistic gardens, coastal restoration and open woodland planting.
Natural habitat:
Occurs naturally in coastal and lowland scrub, open forest, forest margins and disturbed ground.
It colonises a wide range of substrates, including sites that become seasonally waterlogged but dry out during summer. It occasionally extends into coastal mountain ranges to approximately 500 metres above sea level.
Growing environment:
Prefers full sun or light shade in well-drained to seasonally moist soil.
Once established it tolerates wind, coastal exposure, moderate drought and fluctuating soil moisture. Young plants are sensitive to root disturbance and should be planted carefully into their permanent position.
Endemic distribution:
Endemic to New Zealand.
Restricted to the North Island, occurring from Te Paki south to approximately Awakino in the west and East Cape in the east.
Height:
Typically 60 cm–1.5 m, occasionally reaching 2 m
Width:
Approximately 60 cm–1.5 m, spreading slowly through short creeping rhizomes
Flowering:
July–November
Fruiting:
Fruit may be present throughout the year
Uses:
• Native restoration
• Coastal and lowland planting
• Open woodland gardens
• Architectural feature plant
• Erosion control
• Wildlife habitat
• Naturalistic mass planting
• Seasonally wet garden areas
Appearance:
Growth habit:
A stout perennial sedge forming dense, upright tussocks of yellow-green to dark green foliage.
The plant spreads slowly through short, exceptionally hard woody rhizomes. Dead rhizomes persist for long periods and contribute to the dense base of established clumps.
Rhizomes/Stems:
The rhizomes are 5–8 mm thick, shortly creeping, hard and woody.
Numerous rigid, bamboo-like culms rise from the rhizomes and reach 60 cm–2 m tall. They are usually 2–4 mm thick but may broaden to 6 mm near the base.
The lower portions are enclosed by tightly fitting leaf sheaths that become dark brown or almost black with age and develop a smooth, glossy surface near the nodes.
Leaves:
Leaves are numerous and arise mainly along the culms rather than solely from the plant’s base.
The blades are commonly as long as or longer than the stems and may reach about 9 mm wide. They vary from yellow-green to dark green and may be flat or rolled inward.
The leaf surfaces are smooth, but their margins are rough and sharply scabrid, capable of cutting exposed skin.
Flowers:
The flowers are grouped into tall, narrow, many-branched panicles measuring approximately 20–60 cm long.
The panicles are usually rigid and upright, with pale brown branchlets arranged in separated dense clusters along the central axis. Each small spikelet contains a single flower.
Outer floral glumes are pale reddish-brown, while the inner glumes are cream-coloured with ragged red tips. Individual flowers have four stamens and three style branches.
Fruit:
The fruit is a smooth, glossy black nut approximately 3.5–4.5 mm long.
It is oblong to slightly egg-shaped, with a tiny pointed tip, and is conspicuous against the pale brown flowering structures.
Seeds:
The hard nut encloses a single seed.
The fruiting units are dispersed mainly by wind, although gravity and movement through surrounding vegetation may also assist local spread.
Ecology:
Cutty Grass contributes dense structural cover within coastal scrub, open forest and regenerating vegetation. Its tough foliage and closely packed stems provide shelter for native insects, lizards and other small animals.
The hard rhizomes help bind shallow or disturbed soils, while the plant’s tolerance of alternating wet and dry conditions allows it to persist in seasonally variable habitats.
Like other native Gahnia species, it may provide habitat or food for specialised native moths and other invertebrates associated with sedges.
Associated habitats:
Coastal scrub, lowland shrubland, open forest, forest margins, regenerating vegetation, seasonally wet ground and exposed coastal slopes.
Associated plants may include mānuka, kānuka, mingimingi, Coprosma species, cabbage tree, flax, native rushes, sedges and low-growing coastal shrubs.
How to grow:
Plant in full sun or light shade in well-drained or seasonally moist soil. Choose the permanent position carefully, as established plants strongly resent transplantation.
Water regularly during the first growing season but avoid prolonged waterlogging. Once established, plants tolerate moderate dryness and require little maintenance.
Wear gloves and protective clothing when handling mature plants because the rough leaf margins can cause cuts.
Propagation:
Propagation is challenging but may be achieved from fresh seed or carefully handled divisions.
Seed germination is often slow and irregular. Sowing into untreated sawdust or a loose, acidic, free-draining medium has produced good results in some cultivation trials.
Division is risky because the roots and rhizomes dislike disturbance. Any divisions should be taken with a generous root ball and replanted immediately.
Cultural use:
The Māori name Tarangarara is recorded for this species, although detailed traditional uses are not widely documented.
Its tough leaves and stems may have had local practical uses similar to those of other native sedges, but care would have been needed because of the sharply roughened leaf margins.
Garden value:
Cutty Grass is an attractive architectural sedge for naturalistic native gardens, coastal plantings and open woodland settings. Its bamboo-like stems, dense upright foliage and glossy black fruit provide strong texture and year-round structure.
It is best suited to sites where it can remain undisturbed after planting. Once established, it is durable, distinctive and capable of thriving across a broad range of soil and moisture conditions.