Polystichum cystostegia
Common names
mountain shield fern
Biostatus
Native – Endemic taxon
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 | Not Threatened
Category
Vascular
Structural class
Ferns
Flower colours
No flowers
Detailed taxonomy
Genus
Family
Synonyms
Aspidium cystostegia Hook.; Dryopteris cystostegia (Hook.) Kuntze; Polystichum cystostegia
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Other information
Orthography note
The orthography of the species epithet has varied from “cystostegia” to “cystostegium”. The International Plant Names Database has resolved the matter, with the preference for “cystostegia” thus:
“Polystichum cystostegia (Hook.) J.B.Armstr.
Trans. & Proc. New Zealand Inst. 13: 364. 1880 [Apr 1881] (as ‘cystostigium’)
Remarks: The epithet “cystostegia” is a noun in apposition. Etymology: Greek cystis, bladder, sac, and stegos, roof, lid [Basionym protologue: ‘the involucres are unlike those of any other species, being singularly thin and membranaceous, covering the sori with a large (in proportion to the size of the plant) hemispherical peltate bladdery lid.’]’
Etymology
polystichum: Many rows (of sori); from the Greek polus and stikhos; parallel rows of spore cases
cystostegia: Bladder cover (indusium)
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.
POLCYS
Chromosome number
2n = 164
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 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
Otago: 2025 | Regionally Not Threatened
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Conservation Status of Indigenous Vascular Plants in Otago, 2025” Jarvie S et al. (2025) report.