Pterostylis micromega


Pterostylis: winged column

Common Name(s)

Swamp Greenhood

Current Conservation Status

2012 - 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

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


2012 - DP, EF
2009 - CD, DP, EF


Pterostylis micromega Hook.f.



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



Pterostylis polyphylla Colenso, Pterostylis furcata var. micromega (Hook.f.) Hatch


Endemic. North, South and Chatham Islands. Once known from Kaitaia to Wellington, North Nelson and the Chatham Islands. The species is still present in the Huntly Basin, (Waikato), Volcanic Plateau, near Wanganui and in the Wairarapa. A plant was also known, until recently from Knuckle Hill, North West Nelson. That plant appears to have died out naturally. It was last reliably recorded from the Chatham Islands in the late 1800s.


Coastal, lowland to subalpine (0 - 1000 m a.s.l.). A plant of bogs, fens and swamps, ranging from acidic to eutrophic. it often forms colonies of 5-30 plants, ranging from large-leaved non-flowering juveniles through to flowering adults. It can be found growing under willows (Salix spp.).


Orchid 150-380 mm tall. Stem smooth, lower internodes short, becoming progressively longer toward apex. Basal leaves usually in a somewhat loose rosette, though when in exposed conditions then a compact rosette; petiole 5-10 mm; lamina 35-50 mm, pale green to grey-green, broad-elliptic, subacute, margins often but not always finely undulate. Upper leaves sessile, ovate to narrowly ovate, channelled, and weakly keeled, becoming sheathing near flower, upper most often reaching or just overtopping flower. Flower conspicuous, solitary, erect, perianth white or cream. Dorsal sepal, green, 25-40 mm, arcuate, apex acuminate to shortly caudate, ascending to decurved; lateral sepals green and white striped at base, diverging at a narrow angle, apex caudate, overtopping galea. Petals white, shorter than dorsal sepal, acuminate. Labellum red-brown, narrow-triangular, arched, markedly protruding, apex narrowly obtuse. Column much shorter than labellum; stigma narrow-oblong, flat.

Similar Taxa

A distinctive greenhood of wetland habitats whose broad-elliptic leaves usually arranged in a loose rosette, and usually with finely undulating almost crisped margins, and rather large, erect, whitish flower with long tapering, arcuate dorsal sepal immediately separate this greenhood from the other New Zealand Pterostylis species.


November - February

Flower Colours



November – March

Propagation Technique

Difficult. Should not be removed from the wild. Basic orchid mix consists of 2 parts medium coarse sand, ideally clean river sand; 2 parts soil, humus or leaf-mould; 1 part weathered sawdust or rotting wood; 1 part granulated bark. For Pterostylis shade of 50% and pots kept evenly moist.


Drainage of habitat; habitat invasion by weeds (in the Waikato royal fern (Osmunda regalis) seems to be the main weed threat); unrestricted wetland access by stock, and wild animals such as deer, pigs, and possums have proved to be a problem at some sites. Nevertheless this species requires some habitat disturbance to thrive, and soon succumbs if its habitat becomes to densely vegetated.

Chromosome No.

2n = 44

Endemic Taxon


Endemic Genus


Endemic Family


Where To Buy

Not commercially available.

Cultural Use/Importance

This is one of a number of orchids which have successfully colonised habitats now dominated by exotic species. For example in the Waikato several populations have been discovered thriving within the moss mounds developed under grey willow (Salix cinerea).


Fact Sheet prepared from NZPCN by P.J. de Lange 1 October 2003. Description subsequently published in de Lange et al. (2007).

References and further reading

de Lange, P.; Rolfe, J. St George, I. Sawyer J. 2007: Wild orchids of the lower North Island. Department of Conservation, Wellington.

This page last updated on 17 Apr 2014