Māpere
Botanical name: Gahnia setifolia
Synonyms: Lampocarya setifolia
Common name(s): Māpere, Gahnia, Giant Gahnia, Razor Sedge
About:
Gahnia setifolia is a very large, robust native sedge forming imposing tussocks of long, arching, dark green to yellow-green foliage. Mature plants can reach approximately 3 m tall and develop from a thick, woody rootstock.
Its long leaves are notoriously harsh and razor-sharp, giving rise to the common name razor sedge. Large, gracefully drooping panicles of reddish-brown to almost black spikelets rise amongst the foliage, making established plants particularly distinctive.
An endemic species, māpere is widespread throughout the North Island but has a much more restricted South Island distribution in Nelson and the Marlborough Sounds.
Natural habitat:
Coastal to montane habitats, from near sea level to approximately 780 m elevation and possibly higher.
It occurs primarily in lowland light forest, scrub, forest margins and disturbed indigenous forest. It is particularly capable of colonising damp exposed soils following disturbance and is frequently encountered along logging tracks, including those within pine plantations.
It also grows beside streams, rivers, ponds and lakes and sometimes occupies the margins of swamps, bogs and mires.
Growing environment:
Best in full sun to light shade in moist but reasonably well-drained soil. It tolerates seasonally wet conditions and, once established, can flourish across a relatively broad range of environments.
It is particularly well suited to damp clay and disturbed forest soils.
Endemic distribution:
Endemic to New Zealand.
North Island: Widespread throughout.
South Island: Primarily Nelson and the Marlborough Sounds.
Height:
1–3 m
Width:
Approximately 1.5–3 m
Flowering:
November–March
Fruiting:
Fruit may be present throughout the year
Uses:
• Wetland and riparian restoration
• Revegetation projects
• Forest and scrub restoration
• Stream, river, pond and lake margins
• Large-scale native landscaping
• Naturalistic planting
• Architectural foliage
• Wildlife habitat
• Stabilisation and revegetation of disturbed soils
Appearance:
Growth habit:
A massive, densely tufted perennial sedge arising from a stout, woody rootstock. Mature plants form substantial clumps, with long leaves arching outward to create a bold but graceful fountain-like form.
Stems:
Flowering culms are exceptionally stout, generally 10–15 mm in diameter and occasionally reaching approximately 20 mm at their bases.
The culms are approximately equal in length to the foliage and support the large, characteristically drooping flowering panicles.
Leaves:
Leaves are approximately equal to the culms in length and may extend for several metres on large plants.
The blades are dark green to yellow-green above and paler, often slightly glaucous, beneath. They are extremely tough, rough and abrasive.
Leaf margins are strongly rolled inward and armed with sharp teeth. Additional longitudinal rows of teeth occur just inside the margins, making the foliage capable of inflicting surprisingly deep cuts on exposed skin.
The basal leaf sheaths reach approximately 30 cm long and mature to a dull brownish-black.
Flowers:
The flowering structure is a large, robust, conspicuously drooping panicle that can approach 1 m long.
It is extensively branched, with primary branches reaching approximately 40 cm. The numerous spikelets are borne on stalks and are typically dark reddish-brown to almost blackish-brown.
Spikelets are approximately 6–7 mm long and contain two flowers.
Each has six or seven glumes. The outer three or four are sterile and approximately 5–6 mm long. The inner glumes are approximately 4 mm long, initially white with reddish-brown tips before darkening to reddish-brown as the fruit matures.
Fruit:
The nuts are approximately 3.5–4.5 mm long and just under 2 mm wide.
They are elliptic to obovoid, smooth and glossy. Young fruits are yellow to cream, gradually maturing to a characteristic reddish-brown.
The reddish-brown mature nuts are useful for distinguishing Gahnia setifolia from the black-fruited Gahnia xanthocarpa and the distinctly bicoloured fruits of Gahnia rigida.
Seeds:
Seed is contained within the hard nut. Fruiting material may remain on plants throughout the year, with dispersal primarily by wind.
Ecology:
Gahnia setifolia is an important structural component of forest margins, scrublands, riparian habitats and disturbed native vegetation.
It responds particularly well to disturbance and can colonise exposed damp soils following logging or forest clearance. Dense mature tussocks provide substantial cover and habitat for native invertebrates.
Like other large Gahnia species, its tough foliage and dense tussock structure create a distinctive microhabitat within regenerating forest and scrub.
Associated habitats:
Light forest, forest margins, regenerating scrub, cut-over indigenous forest, logging tracks, pine plantation margins, damp clay banks, streamsides, river margins, lake and pond edges, swamp margins, bog margins and mire margins.
In the northern parts of New Zealand it may occur alongside other large native Gahnia species, particularly Gahnia xanthocarpa.
How to grow:
Plant in full sun to partial shade in moist, reasonably well-drained soil. It performs particularly well in damp clay and other moisture-retentive soils but does not require permanently waterlogged conditions.
Allow generous space. Mature specimens are extremely large and their long, razor-edged foliage can extend well beyond the centre of the plant.
For this reason, it should not be planted immediately alongside paths, entrances, children’s play areas or other places where people regularly brush against the foliage.
Once established, plants are hardy and relatively adaptable. Avoid unnecessary transplantation because established Gahnia generally resent root disturbance.
Propagation:
Propagation is primarily from seed but can be challenging.
Fresh seed may be sown, although germination is often slow or erratic. Good results have been achieved by germinating Gahnia seed in untreated sawdust.
Young plants should be handled carefully and grown with minimal disturbance to their root systems.
Division or transplantation of established plants is generally unsuccessful, as plants strongly resent root disturbance and may die following relocation.
Cultural use:
The Māori name māpere is widely applied to this species.
It is also commonly called razor sedge because of its exceptionally sharp, rough-edged leaves. Dense stands can present a significant obstacle when travelling through scrub or forest, and the leaves are capable of cutting exposed skin.
Māpere readily colonises damp clay and disturbed forest soils, including ground exposed following logging, and can consequently become a conspicuous feature of regenerating vegetation.
Garden value:
Gahnia setifolia is a spectacular native sedge for large gardens, ecological plantings and naturalistic landscapes.
Its immense arching foliage and large drooping reddish-brown flower heads give it considerably more visual presence than most native sedges. It is particularly effective beside ponds, streams and larger water features or planted through expansive native restoration areas.
Its size and extremely sharp foliage need to be considered carefully when selecting a planting position. Given adequate room, māpere develops into an impressive architectural specimen with a strongly natural New Zealand character.