Thelypteris confluens
Common names
marsh fern, swamp fern
Biostatus
Native
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | At Risk – Declining | Qualifiers: DPS, DPT, TO
Category
Vascular
Structural class
Ferns
Flower colours
No flowers
Detailed description
Long-rhizomatous, tufted fern. Often winter dormnant and summer-green in cooler habitats. Stipes 100–500 mm long, yellow-brown, wiry, clad in sparse scales. Fronds 150–350 × 50–130 mm, pale green, yellow-green to dark-green, stiffly erect, rather brittle, fertile fronds slightly smaller than sterile. Pinnae in 15–20–(30) pairs, the longest 30–70 × 7–12 mm, fertile shorter and narrower, divided almost to midrib into onlong, round-ended, ultimate segments. Indusia with sparse to dense glandular hairs.
Similar taxa
None
Distribution
Indigenous. New Zealand: North Island (Te Paki to the Waitakere Ranges in the west and Bay of Plenty in the east). Mainly near the coast but extending inland within wetlands associated with geothermally active systems. Outside New Zealand reported widely from Africa, India and Australia but apparently now highly threatened and close to extinction in Australia.
Habitat
Coastal, lowland and geothermally active eutrophic wetlands. Often found growing on the margins of lakes and slow flowing streams where it grows within “floating suds” that have developed from organic matter trapped amongst rafts of swamp millet grass (Isachne globosa) and raupo (Typha orientalis).
Threats
Formerly common in lowland coastal wetlands, this species remains abundant only inthose more remote western wetlands from the Kaipara Harbour north to Te Paki. It is close to extinction and highly threatened in the Bay of Plenty, with perhaps the largest populations now left on remote Matakana Island. The main threat seems to come from wetland drainage, eutrophication and the often associated spread of faster, taller growing weeds. The species is also popular with fern collectors, and some of the better known and more accessible populations have been depleted or destroyed through fern collection. According to the recent Australian Fern Flora treatment of this species the best populations in Australasia now occur in New Zealand. Its future is not assured in Australia.
Detailed taxonomy
Genus
Family
Synonyms
Pteris confluens Thunberg, Aspidium thelypteris var. squamigerum Schldl., Aspidium squamigerum (Schldl.) Fee., Thelypteris palustris var. squamigera (Schldl.) Weath., Thelypteris squamigera (Schldl.) Ching, Nephrodium squamulosum Hook.f., .
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
Spore bearing fronds may be found throughout the year
Fruiting
Spore bearing fronds may be found throughout the year
Propagation technique
Easy from the division of whole plants and probably from fresh spores. Needs permanantly wet ground and does best in sunny sites within a pond or in partially submerged pots.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Other information
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for June 2024 for the full story.
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
THECON
Chromosome number
2n = 70
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | At Risk – Naturally Uncommon | Qualifiers: PD, TO
2012 | At Risk – Naturally Uncommon | Qualifiers: PD, TO
2009 | At Risk – Declining | Qualifiers: TO
2004 | Gradual Decline
Regional conservation statuses
Auckland: 2025 | Regionally Threatened – Regionally Vulnerable | Qualifiers: Sp, DPT, PF, RR, TO
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Auckland conservation status information is sourced from the “Conservation status of vascular plant species in Tāmaki Makaurau / Auckland” Simpkins E et al. (2025) report.
Referencing and citations
References and further reading
Brownsey PJ, Smith-Dodsworth JC. 2000. New Zealand Ferns and Allied Plants. David Bateman, Auckland, NZ. 168 p.
Cameron EK, Bellingham RM. 1998. Thelypteris confluens an addition to the Waitakeres. Auckland Botanical Society Journal 53: 38.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (21 April 2011). Description adapted from Brownsey & Smith-Dodsworth (2000).