Hymenophyllum rarum


Hymenophyllum: Membranous leaf, from the Greek humen and phullon
rarum: thin leaved; from the Latin rarus

Common Name(s)

filmy fern

Current Conservation Status

2012 - Not Threatened

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 - Not Threatened
2004 - Not Threatened


Hymenophyllum rarum R. Br.



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



Mecodium rarum (R. Br.) Copel.; Hymenophyllum imbricatum Colenso; Hymenophyllum semibivalve Hook. et Grev.


Indigenous. New Zealand: North, South, Stewart, Chatham and Auckland Islands. Also Australia


Coastal to montane. Common throughout the country in close forest, scrub, on shaded cliff faces, amongst boulders and in rubble slopes. Rather drought tolerant and often found growing in very exposed sites.


Terrestrial or epiphytic, aromatic fern forming extensive, interwoven, creeping patches. Rhizomes long-creeping, very thin, brittle. Fronds pale grey-green (glaucescent). Stipes 20-70 mm long, very thin, wiry when fresh, very brittle when dry, glabrous, not winged; rachises very narrowly winged in upper part. Laminae 20-120 × 10-30 mm, narrowly ovate, narrowly elliptic, rarely deltoid, usually 2-pinnate, membranous, glabrous. Ultimate segments oblong, imbricate, margins smooth. Sori terminating the uppermost ultimate segments, ovoid completely immersed in lamina, few on each primary pinna, mostly confined to upper part of frond. Indusium flaps entire. Description adapted from Brownsey & Smith-Dodsworth (2000).

Similar Taxa

Easily recognised by the peculiar grey-green, small, membranous fronds; by the smooth margins of the pinnae, ultimate segments and indusia; and by the sori which are sunk within the uppermost segments of the uppermost pinnae. Australian plants of H. rarum (which include the type of this species) are rather different differing by the non-aromatic, widely spaced rather than imbricating pale green, pinnae. The sori of Australian H. rarum are almost not wholly immersed within the pinnae nor confined to the uppermost segments of the uppermost pinnae. It seems likely that New Zealand plants referred to H. rarum may warrant recognition as a separate species. Further study into this matter is needed.



Flower Colours

No Flowers



Propagation Technique

Difficult - should not be removed from the wild.


Not Threatened

Chromosome No.

2n = 72

Endemic Taxon


Endemic Genus


Endemic Family


Life Cycle and Dispersal

Minute spores are wind dispersed (Thorsen et al., 2009).

Where To Buy

Not commercially available



Fact sheet prepared for NZPCN by P.J. de Lange (20 April 2011). Description adapted from Brownsey & Smith-Dodsworth (2000).

References and further reading

Brownsey, P.J.; Smith-Dodsworth, J.C. 2000: New Zealand Ferns and Allied Plants. Auckland, David Bateman

Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285-309

This page last updated on 30 May 2015