Carrier Tangle Fern

Botanical name: Gleichenia microphylla
Synonyms: Gleichenia circinnata var. microphylla, Gleichenia microphylla var. semi-vestita, Gleicheniastrum microphyllum var. semi-vestitum, Gleicheniastrum semi-vestitum, Mertensia microphylla, Gleichenia circinnata var. semi-vestita, Calymella semi-vestita, Gleichenia semi-vestita, Gleicheniastrum microphyllum, Calymella microphylla
Common name(s): Carrier tangle fern, Parasol fern, Scrambling coral fern, Umbrella fern, Matua-rarauhe, Matuku, Tapuwae kōtuku, Waewae kākā, Waewae kōtuku, Waewae matuku

About:
A distinctive scrambling fern that forms extensive, often almost impenetrable tangles of repeatedly forked fronds. Gleichenia microphylla spreads through long-creeping underground rhizomes and is particularly characteristic of damp, acidic and nutrient-poor ground. Its small, flat, triangular to oblong leaf segments and conspicuous bright yellow sporangia help distinguish it from the closely related tangle fern, Gleichenia dicarpa.

Natural habitat:
Occurs mainly in coastal and lowland habitats on impoverished or poorly developed soils. Typical sites include swamps, wet open ground, clay pans, coastal cliff seepages, stream margins, exposed banks, ferricrete and ultramafic or serpentinite substrates. It can also occur on thermally heated ground, where it may form extensive ground cover within open scrub.

Growing environment:
Best suited to consistently moist to wet, acidic soils with high humidity and good light. It tolerates nutrient-poor substrates and periodically waterlogged conditions but strongly resents root disturbance. Established colonies may grow in full sun or partial shade where adequate moisture is available.

Endemic distribution:
Indigenous but not endemic to New Zealand. Found throughout the North Island, South Island and Stewart Island/Rakiura, although often scarce or absent from drier eastern districts. It is particularly common in northern and western areas. Also occurs in Australia, with records from parts of South-East Asia requiring some taxonomic clarification.

Height:
Fronds approximately 0.1–2 m tall, sometimes developing into much larger scrambling masses where conditions are favourable.

Width:
Indefinite. Long-creeping rhizomes allow colonies to spread extensively and form broad, dense tangles.

Flowering:
Not applicable — a fern that reproduces by spores rather than flowers.

Fruiting:
Not applicable — spores are produced within sporangia grouped into sori on the undersides of fertile fronds.

Uses:
• Wetland and swamp restoration
• Pakihi and acidic wetland planting
• Naturalistic fern gardens
• Revegetation of damp, nutrient-poor ground
• Habitat and structural cover for wetland invertebrates and other small fauna
• Specialist planting on acidic or ultramafic substrates

Appearance:
Growth habit:
A terrestrial, rhizomatous fern forming extensive scrambling colonies. The long-creeping rhizomes produce widely spaced fronds whose axes repeatedly fork at broad angles. A growing bud occurs between each pair of branches and can continue extending to form another tier, allowing individual fronds to develop a characteristic tiered, umbrella-like structure.

Leaves:
Fronds are approximately 90 mm to 2 m long and generally consist of one to three tiers of branches. The ultimate branches carry numerous closely arranged pinnules. Individual segments are approximately 1–2.7 mm long and 0.8–2 mm wide, oblong, ovate or triangular and usually flat, although they may become slightly recurved when dry. Both surfaces are green, with the underside generally somewhat paler.

Flowers:
None. As a fern, Gleichenia microphylla does not produce flowers.

Fruit:
None. Fertile fronds bear circular sori on their undersides. Each sorus usually contains 2–4 conspicuous bright yellow sporangia, occasionally more. The sori remain superficial rather than being embedded in the frond tissue. Minute spores are dispersed by wind.

Ecology:
An important colonising fern of wet, open and nutrient-poor environments. Its creeping rhizomes and densely interwoven fronds can produce extensive colonies that protect the soil surface, trap organic material and provide shelter within swamp, seepage and wetland communities. It is particularly well adapted to acidic substrates where many larger competing plants struggle to establish.

Associated habitats:
Swamps, pakihi, clay pans, coastal seepages, stream margins, wet banks, ferricrete, ultramafic and serpentinite ground, geothermal areas and open wet scrub. It commonly occurs with other moisture-tolerant ferns, sedges, rushes and low-growing wetland shrubs.

How to grow:
A specialist species that can be difficult to establish in cultivation. It requires consistently moist, preferably acidic soil and is best grown where its roots and rhizomes can remain undisturbed. A sheltered, humid site with good light or partial shade is preferable. Once established, plants can spread considerably and should be given room to form their naturally tangled colonies.

Propagation:
Propagation from spores is possible but slow and requires appropriate humid conditions. Transplanting established plants is unreliable because the rhizomes and roots are highly sensitive to disturbance. If attempted, divisions should retain a substantial amount of intact rhizome and surrounding soil and must be kept continuously moist during establishment.

Cultural use:
Several Māori names have been recorded for this fern, including matua-rarauhe, matuku, tapuwae kōtuku, waewae kākā and waewae kōtuku. Specific traditional uses are not well documented, so cultural associations should not be inferred beyond recorded names without further evidence.

Garden value:
An unusual and highly architectural native fern best suited to specialist wetland, bog and naturalistic gardens. Its repeatedly forked, umbrella-like fronds create a distinctive texture unlike most other New Zealand ferns. It is particularly valuable for difficult wet, acidic and nutrient-poor sites, although its vigorous rhizomatous spread and sensitivity to transplantation make it better suited to larger naturalistic plantings than conventional garden beds.