Pterostylis micromega
Common names
swamp greenhood
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Orchids
Flower colours
Green, White
Detailed description
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, uppermost 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.
Distribution
Endemic. New Zealand: North Island (once known from Kaitaia to Wellington, the species is still present in the Huntly Basin, (Waikato), Volcanic Plateau, near Wanganui and in the Wairarapa), South Island (a plant was also known until recently from Knuckle Hill, North-west Nelson but it appears to have died out naturally), Chatham Islands (last reliably recorded in the late 1800s). This is one of a number of orchids that have successfully colonised habitats now dominated by exotic species. For example several populations in Waikato have been discovered thriving within the moss mounds developed under grey willow (Salix cinerea).
Habitat
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.).
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Threatened – Nationally Critical | Qualifiers: DPR, DPT, EF, PF, RR
Threats
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 too densely vegetated.
Detailed taxonomy
Family
Synonyms
Pterostylis polyphylla Colenso, Pterostylis furcata var. micromega (Hook.f.) Hatch
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
November–February
Fruiting
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.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Other information
Etymology
pterostylis: Winged column
Manaaki Whenua Online Interactive Key
NVS 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.
PTEMIC
Chromosome number
2n = 44
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Threatened – Nationally Endangered | Qualifiers: DP, EF, RR
2012 | Threatened – Nationally Endangered | Qualifiers: DP, EF
2009 | Threatened – Nationally Critical | Qualifiers: CD, DP, EF
2004 | Threatened – Nationally Critical
Referencing and citations
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, NZ. 194 p.
Attribution
Fact Sheet prepared from NZPCN by P.J. de Lange 1 October 2003. Description subsequently published in de Lange et al. (2007).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Pterostylis micromega Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/pterostylis-micromega/ (Date website was queried)