Tmesipteris horomaka


Tmesipteris: From the Greek tmesis (cutting) and pteris (fern), alluding to the forked appendages on fertile fronds

Common Name(s)

Banks Peninsula fork fern

Current Conservation Status

2018 - Threatened - Nationally Endangered

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

2012 - Threatened - Nationally Critical
2009 - Threatened - Nationally Critical
2004 - Threatened - Nationally Critical


2012 - RR
2009 - DP, OL


Tmesipteris horomaka Perrie, Brownsey, et Lovis



Flora Category

Vascular - Native

Structural Class



None (first described in 2010)


Endemic. New Zealand: South Island, Banks Peninsula


An epiphyte mostly found on the trunks of the tree ferns ponga (Cyathea dealbata), Smith's tree fern (C. smithii) and wheki (Dicksonia squarrosa) within enclosed forest. It has also been collected once within the rich peaty soil produced by a species of harakeke/flax (Phormium sp.) growing on a cliff face.


Epiphytic or rarely terrestrial plants. Aerial stems pendulous, 70-510 mm long, not known to branch within the leafy part of the stem. Leaves spirally arranged, narrowly oblong to narrowly ovate, linear to falcate(-sigmoid), 10-25 x 2.5-6.5 mm; apex emarginate, truncate or cuspidate, with mucro 1-2 mm long. Synangia 2.5-6 x 1-2 mm, rounded to slightly biconic, with the lower surface of the sporangia appressed along all or most of their length to the subtending leaf margin, and points where present projecting laterally. Spores 71-83 x 35-39 microns. Description adapted from Perrie et al. (2010).

Similar Taxa

Tmesipteris horomaka is distinguished from T. elongata by its emarginate to truncate leaf apices and from T. tannensis by its more rounded synangia that do not project upwards from their subtending leaf. Tmesipteris horomaka is also distinguished from both these species by its octoploid chromosome number and generally larger spore size.


Not applicable - spore producing

Flower Colours

No Flowers


Not applicable - spore producing

Propagation Technique

Difficult - should not be removed from the wild.


Currently known from 11 sites and an estimated c.75 plants based on the eight populations visited by Perrie et al. (2010). Therefore Tmesipteris horomaka easily qualifies for Threatened/Nationally Critical as there are less 250 mature individuals known. On the advice of Leon Perrie Tmesipteris horomaka had already been listed as Nationally Critical by de Lange et al. (2009) under the name Tmesipteris aff. tannensis (CHR 496779; Banks Peninsula) .

Chromosome No.

2n = c.416

Endemic Taxon


Endemic Genus


Endemic Family


Where to Buy

Not commercially available.

Tmesipteris horomaka


Fact sheet prepared for the NZPCN by\ P.J. de Lange (5 May 2010).

References and further reading

de Lange, P.J.; Norton, D.A.; Courtney, S.P.; Heenan, P.B.; Barkla, J.W.; Cameron, E.K.; Hitchmough, R.; Townsend, A.J. 2009: Threatened and uncommon plants New Zealand Journal of Botany 47: 61–96.

Perrie, L.R.; Brownsey, P.J.; Lovis, J.D. 2010: Tmesipteris horomaka, a new octoploid species from Banks Peninsula. New Zealand Journal of Botany 48: 15-29.

Townsend, A.J.; de Lange, P.J.; Norton, D.A.; Molloy, J.; Miskelly, C.; Duffy, C. 2008: The New Zealand Threat Classification System manual. Wellington, Department of Conservation.

This page last updated on 19 Jan 2014