Dicranopteris linearis var. linearis


linearis: linear (leaves)

Common Name(s)

tangle fern

Current Conservation Status

2012 - At Risk - Naturally Uncommon

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 - Naturally Uncommon
2004 - Range Restricted


2012 - RR, SO
2009 - SO


Dicranopteris linearis (Burm.f.) Underw. var. linearis



Flora Category

Vascular - Native

NVS Species 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.

Structural Class



Gleichenia linearis (Burm. f.) C.B. Clarke; Polypodium lineare Bruman, Polypodium dichotomum Thunb., Mertensia dichotoma Willd.


Indigenous. In New Zealand known only from the North Island, where it grows on geothermally heated ground from Rotorua to Karapiti near Taupo


In New Zealand confined to geothermally active sites where it grows on heated soils, sinter field, and around geysers, hot pools, and steam vents.


Terrestrial fern. Rhizomes long-creeping, hairy. Fronds up to 0.3 m tall finely hairy with hairs irregularly branched; veins free. Stipes glaucous-brown to pale brown, persistent when dead, glabrous, terminated by a bud. Rachises of fronds in 1-2-tiers, forking 2-3x at narrow angles with a bud terminating each fork, the ultimate branches pinnate, narrowly elliptic, 0.1-0.4 m long. Pinnae linear 10-40 x 2.5-5 mm, notched at apices, margins smooth, fused at base, pale green to yellow green to slightly glaucous green above, whitish to glaucescent below. Sori in one row either side of midrib and well away from pinna margins, comprising 6-10 pairs of sporangia, indusia absent.

Similar Taxa

Distinguished from the distinctly related New Zealand species of Sticherus C.Presl and Gleichenia J.E.Smith by its hairyrather than scaly rhizomes, pinnae confined to ultimate branches rather than on all rachis branches, irregularly branched lamina hairs, and by the sporangia in groups of 6-10 rather than in groups of 2, 2-4 or in rows either side of the midrib. It is the only species of the New Zealand representatives of the family Gleicheniaceae to be completely confined to geothermal sites.


Not applicable - spore producing

Flower Colours

No Flowers


Not applicable - spore producing

Propagation Technique

Easy from rooted pieces. Once established grows quickly. Prefers a sunny site in damp soil. Frost and cold sensitive


Not threatened. Natrurally confined to sites of geothermal acitivity within the Taupo Volcanic Zone. Rather tolerant of extreme heat and able to withstand shading. This species has actively colonised newly created geothermal fields such as Karapiti. It is possible some smaller populations might be threatened by introduced weeds tolerant of heated soils but there is no hard evidence available to confirm this.

Chromosome No.

2n = c.160

Endemic Taxon


Endemic Genus


Endemic Family


Where To Buy

Not commercially available.

Taxonomic notes

New Zealand plants appear to represent a distinct cytorace. This needs further investigation.

This page last updated on 26 Aug 2013