Species

Nephrolepis flexuosa

Etymology

Nephrolepis: Kidney scale
flexuosa: flexuous

Common Name(s)

native ladder fern

Current Conservation Status

2012 - At Risk - Declining

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - At Risk - Declining
2004 - Range Restricted

Qualifiers

2012 - RR, SO
2009 - RR, SO

Authority

Nephrolepis flexuosa Colenso

Family

Nephrolepidaceae

Flora Category

Vascular - Native

NVS Species Code

NEPFLE

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.

Structural Class

Ferns

Synonyms

Nephrolepis var. pseudolauterbachii Hovenkamp et Miyam. appears to be a new name for the same species in the Polynesian part of its range; Nephrolepis auriculata (L.) Trimen

Distribution

Indigenous. Known with certainty from New Zealand, Raoul, Norfolk and Lord Howe Islands, and also Fiji and Rarotonga. This species may also be in Samoa and Sri Lanka and it is probably wide ranging throughout the Indian and Pacific Oceans. It may also be in Australia.

Habitat

Abundant in coastal forest and scrub on Raoul Island, otherwise in New Zealand confined to the North Island where it is only known from active geothermal fields from about Kawerau south to the Rotorua Lakes District to Lake Taupo, where it reaches a world southern limit at Tokaanu near Turangi.

Features

Rhizomes short, erect, stoloniferous. Stolons without tubers. Fronds pinnate, at first erect but tending to droop with age (0.1-)0.8-1(-1.5) m x (10-)20(-50) mm (including stipes); yellow-green to dark green, narrowly lanceolate, gradually tapering toward apex; rachis bearing subulate scales, margins fringed with many short hair-like processes. Pinnae in 50-60(-80) or more pairs, deltoid-oblong or oblong, subsessile, closely adjacent and overlapping rachis, often with an enlarged basal auricle. Sterile pinnae (5-)10-15(-25) x (4-)6(-10) mm; margins entire to subentire, crenulate or serrated towards apex. Fertile pinnae distinctly shorter, margins crenulate (rarely serrated). Sori submarginal, indusia reniform, opening toward pinna apex.

Similar Taxa

Frequently confused with the naturalised and highly aggressive N. cordifolia, from which it is easily distinguished by its non-tuberous habit. Both species also differ by their chromosome number, 2n = 82 in N. cordifolia and 2n = 164 in N. flexuosa, and by their spore morphology and size. N. flexuosa tends to have narrower more gracile fronds which are typically drooping, while those of N. cordifolia are wider, stouter and invariably rigidly erect.

Flowering

Spore bearing fronds may be found throughout the year

Flower Colours

No Flowers

Fruiting

Spore bearing fronds may be found throughout the year

Propagation Technique

Easy from division of whole plants, and also from fresh spores, which take about 6-8 months to fertilise and produce young plants.

Threats

Very common on Raoul Island. In the North Island it is confined to active geothermal fields where it can be locally common, though more often than not it is scarce. At least one population near Kawerau is threatened by the spread of N. cordifolia which has become well established at that site. Many populations are threatened by the spread of black berry (Rubus fruticosus agg.) and other weeds, and at least one has gone extinct over the last ten years. 

Chromosome No.

2n = 164

Endemic Taxon

No

Endemic Genus

No

Endemic Family

No

Where To Buy

Very rarely available from some specialist native plant nurseries.

Taxonomic Notes

Hovenkamp & Miyamoto (2005) treat Nephrolepis flexuosa as a synonym of N. cordifolia var. cordifolia. For N. cordifolia they indicate that the presence or absence of tubers has no taxonomic importance. They then recognise a distinct non-tuberous variety N. cordifolia var. pseudolauterbachii from the mid Pacific islands. However plants of  ar. pseudolauterbachii from Fiji had already been referred to N. flexuosa by de Lange et al. (2005), treated in that paper as distinct from N. cordifolia s.s. because of its lack of tubers, larger spores and distinctive tetraploid chromosome number (2n = 164). Thus the relegation of N. flexuosa by Hovenkamp & Miyamoto (2005) into synonymy with diploid N. cordifolia, yet apparent recognition of it (N. flexuosa) as the tetraploid var. pseudolauterbachii is inconsistent. At this stage NZPCN see no reason not to retain N. flexuosaas a valid indigenous New Zealand species.
 



Attribution

Fact Sheet by P.J. de Lange 7 December 2005. Description based on Brownsey and Dodsworth (2000) supplemented with observations made from herbarium specimens

References and further reading

Brownsey, P.J.; Smith-Dodsworth, J.C. 2000: New Zealand ferns and allied plants. David Bateman Ltd, Auckland

de Lange, P.J.; Gardner, R.O.; Sykes, W.R.; Crowcroft, G.M.; Cameron, E.K.; Stalker, F.; Christian, M.L.; Braggins, J.E. 2005: Vascular flora of Norfolk Island: some additions and taxonomic notes. New Zealand Journal of Botany 43: 563-596.

Hovenkamp, P.H.; Miyamoto, F. 2005: A conspectus of the native and naturalized species of Nephrolepis (Nephrolepidaceae) in the world. Blumea 50: 279-322.

This page last updated on 22 Aug 2017