Mecodium rarum (R. Br.) Copel.; Hymenophyllum imbricatum Colenso; Hymenophyllum semibivalve Hook. et Grev.
Vascular – Native
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.
2n = 72
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
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).
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.
Minute spores are wind dispersed (Thorsen et al., 2009).
Difficult - should not be removed from the wild.
hymenophyllum: Membranous leaf, from the Greek humen and phullon
rarum: Thin leaved; from the Latin rarus
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
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Hymenophyllum rarum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/hymenophyllum-rarum/ (Date website was queried)