Austroblechnum norfolkianum
Biostatus
Native
Category
Vascular
Structural class
Ferns
Flower colours
No flowers
Detailed description
Tufted fern. Rhizomes stout, erect. Covered in old stipe ends. Stipes of sterile fronds 50–150 mm long, scaly at base. Sterile laminae narrowly elliptic, pinnate, 350–900 × 90–180 mm, dark green to bright green, never red-tinged. somewhat fleshy, upper surfaces shining, glabrous. Sterile pinnae in 35–60 pairs, longest at the middle, 50–90 × 8–18 mm, falcate and tapering to acute apices, gradually reducing to short flanges at base, margins finely toothed, bases adnate. Fertile fronds only slightly shorter than sterile.
Similar taxa
Most often confused with Austroblechnum lanceolatum, from which it is most reliably distinguished by its dark green to bright green, somewhat fleshy fronds, which are never red or pink-tinged, by the distinctly sickle-shaped (falcate) pinnules and much shorter fertile fronds (these are usually half the length of the sterile fronds). In New Zealand A. norfolkianum is an offshore island species, usually found in or near petrel burrows in deeply shaded forest or in rocky sites within overhands and damp recesses.
Distribution
Indigenous. Common on Raoul Island (Kermadec Island group) and Manawatāwhi / Three Kings Islands, otherwise uncommon and sparingly distributed on mainly offshore islands from the Cavallis south to Mayor Island / Tuhua. Known on the Chatham Islands from South East Island (Rangatira). Also on Norfolk Island where it is now seriously at risk of extinction.
Habitat
Strictly Coastal. This species is most frequently seen on the outer Hauraki Gulf offshore islands, and on the more remote Manawatāwhi / Three Kings Islands and Kermadec Islands. It favours shaded sites, usually in or near petrel colonies, or near penguin trails and nests.
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 – Naturally Uncommon | Qualifiers: TO
Threats
Not threatened in New Zealand, although close to extinction on Norfolk Island. In New Zealand it has a primarily northern offshore island distribution, and is by and large uncommon except on the Kermadec Islands and Manawatāwhi / Three Kings Islands.
Detailed taxonomy
Genus
Family
Synonyms
Lomaria norfolkiana Heward, Blechnum lanceolatum var. norfolkianum (Heward) Laing, Blechnum norfolkianum (Heward) Maiden nom. superf., nom. illeg., Lomaria acuminata Baker nom. illeg. non Desv. (1811), nec C.Presl. (1825), Spicanta acuminata (Baker) Kuntze, nom. illeg., Blechnum acuminatum (Baker) Maiden nom. illeg. non Fée (1852), nec Sturm (1853); Lomaria attenuata sensu Hook.f.; Blechnum norfolkianum (Heward) C.Chr.
Taxonomic notes
Perrie et al. (2014) advocated for a broadened circumscription of Blechnaceae whereby a number of genera traditionally recognised as distinct from Blechnum were merged within it. However, this view has not met with universal acceptance (see Gasper et al. 2016) and does not seem to be followed worldwide (PPG 2016). From a New Zealand perspective the decision to merge Doodia in Blechnum, and rejection of Diploblechnum has not been universally accepted either e.g., Wilcox & Warden (2017), and as such it is considered appropriate to follow world opinion and accept the taxonomy of Gasper et al. (2016) and recommendations of the PPG (2016). See also the comments by Pyner (2017).
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
Not applicable—spore producing
Fruiting
Not applicable—spore producing
Propagation technique
Easy from fresh spores. Does best in a sheltered spot planted within free draining, fertile, moist soil. Responds well to frequent mulching with partially rotted leaf litter.
Other information
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.
BLENOR
Chromosome number
2n = c.66
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: TO
2012 | At Risk – Naturally Uncommon | Qualifiers: TO
2009 | At Risk – Naturally Uncommon | Qualifiers: TO
2004 | Sparse
Regional conservation statuses
Auckland: 2025 | Regionally Threatened – Regionally Endangered | Qualifiers: DPR, DPS, 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.
Gasper AL, de Oliveira Dittrich VA, Smith AR, Salino A. 2016. A classification for Blechnaceae (Polypodiales: Polypodiopsida): New genera, resurrected names, and combinations. Phytotaxa 275: 191–227. https://doi.org/10.11646/phytotaxa.275.3.1.
Perrie LR, Wilson RK, Shepherd LD, Ohlsen DJ, Batty EL, Brownsey PJ, Bayly MJ. 2014. Molecular phylogenetics and generic taxonomy of Blechnaceae ferns. Taxon 63(4): 745–758. https://doi.org/10.12705/634.13.
PPG 1: The Pteridophyte Phylogeny Group 2016. A community-derived classification for extant lycophytes and ferns. Journal of Systematics and Evolution 54: 563–603. https://doi.org/10.1111/jse.12229.
Pyner T. 2017. A new classification of Blechnum. British Pteridological Society. https://ebps.org.uk/new-classification-blechnum/. Accessed [INSERT DATE ACCESSED].
Wilcox M, Warden J. 2017. Botany of Hillsborough coast bush reserves, Manukau Harbour, Auckland. Auckland Botanical Society Journal 72: 32–46.
Attribution
Fact Sheet by P.J. de Lange 6 June 2005. Description from Brownsey & Smith-Dodsworth (2000).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Austroblechnum norfolkianum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/austroblechnum-norfolkianum/ (Date website was queried)