Alsophila kermadecensis
Common names
Kermadec tree 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 | At Risk – Naturally Uncommon | Qualifiers: IE, OL
Category
Vascular
Structural class
Ferns
Simplified description
Tall tree fern with green-stalked soft leaves to 4 m long inhabiting Raoul Island in the Kermadec Islands. Trunk to 20 m tall, slender, old leaves fall off whole. Leaf stems covered in small star-tipped scales and pointed scales (lens needed). Sporangia arranged in small half capsules underneath fronds.
Detailed description
Gracile tree fern up to 20 m tall. Trunk slender, often curved, covered with diamond-shaped stipe scars. Stipes slender, copiously invested in woolly hairs and pale brown to brown scales lacking marginal spines. Fronds arching from crown, up to 4 × 2 m, 3-pinnate; dead fronds falling. Primary pinnae up to 400 mm long, dark green to yellow-green above, subcoriaceous to membranous, undersides paler, bearing numerous scales; scale apices terminated by single or stellate spines. Indusia cucullate.
Similar taxa
On Raoul Island this species is sympatric with Alsophila milnei, from which it is easily distinguished by its taller, more slender trunk which lacks a persistent skirt of dead frond and bears numerous rhomboid stipe scars; by the soft rather than coriaceous, raching rather than horizontal fronds, and hood-shaped rather than cup-shaped indusia. The scales on the underside of the pinnae in A. kermadecensis are not curled and are terminated by a single or stellate spine. Alsophila kermadecensis is very closely related to A. cunninghamii, which is common in New Zealand proper and Australia. From that species Alsophila kermadecensis is best distinguished by its clean trunks which lack persistent stipe bases, less divided fronds and by the absence of stellate hairs on the frond undersides.
Distribution
Endemic. Kermadec Islands, Raoul Island only
Habitat
Confined to the higher parts of Raoul Island where it is a locally conspicuous component of ravine, gully, gorge and cliff forest in the wetter part of the island.
Threats
Not Threatened. Listed because it is a narrow range naturally confined to Raoul Island. In the past it had been regarded as highly threatened but in recent years numerous plants of all different age classes have been found.
Detailed taxonomy
Genus
Family
Synonyms
Cyathea kermadecensis W.R.B. Oliv.;
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Propagation technique
Easily grown from spores. Young plants are very cold sensitive and will not tolerant any frost, wind or drought. They are best planted in a warm, sheltered, permanently damp site. Once established this species is very fast growing.
Other information
Cultivation
Occasionally available from specialist native and general plant nurseries.
Etymology
kermadecensis: From the Kermadec Islands
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.
CYAKER
Chromosome number
2n = 138
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: IE, OL
2012 | At Risk – Naturally Uncommon | Qualifiers: IE, OL
2009 | At Risk – Naturally Uncommon | Qualifiers: RC, IE, SO
2004 | Range Restricted
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.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange July 2009. Description adapted from Brownsey & Smith-Dodsworth (2000).