Pterostylis irsoniana
Common names
greenhood
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Orchids
Simplified description
Green ground-dwelling leafy herb up to 25-35 cm tall. Flower mostly green and white and can be quite colourful with fine detailed stripes of red or orange. The labellum is mostly and uniquely shaped tapering with curled tip. The labellum can also be triggered, making it flick back inside the flower.
Flower colours
Green, Red/Pink, White
Detailed description
Terrestrial, summer-green, tuberous perennial herb. Plants solitary or in colonies, up to 350 mm tall when flowering. Stem stout, erect, terete, smooth, internodes less than leaves, dark green to reddish green. Leaves 3-5(-8) increasing in size from base to top, uppermost leaves overtopping flower; largest leaf on stem (40-)150-200 × 5-12(-8) mm; dark green to yellow-green, often tinged with red or pink, linear-lanceolate, widest near sheathing base, tapering to an acuminate apex; more or less keeled, midrib prominent, yellow to yellow-cream lateral veins less obvious. Flower solitary, reddish green. Ovary erect to slightly inclined, dark green, deeply ribbed, ribs often reddish. Dorsal sepal (15-) 25 - 30 mm long, the erect part usually longer than the rest, apex acuminate to shortly caudate; lateral sepals diverging at a narrow angle, apices acuminate to shortly caudate, not greatly exceeding the galea. Petals slightly shorter than dorsal sepal, apices narrow-acuminate. Labellum narrowly deltoid and protruding, gently arched but consistently curled sharply downward at the narrow, cucullate, deeply emarginate apex; midrib not evident in distal portion, proximally prominent and more or less papillose or bearing sparse calli, terminating basally in a prominent, projecting dark red to maroon-black callus. Column almost as long as labellum; stigma long and narrow.
Similar taxa
The distinctive curled labellum with an deeply emarginate tip (like a drainers scoop), and prominent dark medial basal callus facing the column are key distinctions that separate this species for all other Pterostylis in New Zealand. The flowers are usually dark green tinged with red.
Distribution
Endemic. New Zealand: North Island (from East Cape South to Wellington), South Island (mainly in the West to about Haast).
Habitat
Lowland to subalpine (montane to subalpine in the northern part of range) up to 1200 m.a.s.l. In beech (Nothofagaceae) forest, podocarp forest, frost flats and subalpine scrub. Often in deep drifts of leaf litter or on the margins of sphagnum bogs.
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 | Not Threatened
Detailed taxonomy
Genus
Family
Synonyms
None (first described in 1950)
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–January
Fruiting
December–April
Propagation technique
Difficult—should not be removed from the wild. asic 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.
Other information
Etymology
pterostylis: Winged column
irsoniana: A construct of two surnames created by Orchidologist Edwin Hatch, to acknowledge both Bruce Irwin and Owen Gibson for their efforts in furthering knowledge of New Zealand orchids. ir = Irwin; son = Gibson.
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.
PTEIRS
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 | Not Threatened
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Referencing and citations
References and further reading
de Lange P, Rolfe J, St George I, Sawyer J. and Dawson M, 2007. Wild Orchids of the Lower North Island: Field guide 2007. Published by the Department of Conservation, Wellington Conservancy, New Zealand. Pp. 138-139.
Moore LB, Edgar E. 1970. Flora of New Zealand, Volume II. Indigenous Tracheophyta: Monocotyledones except Gramineae. Government Printer, Wellington, NZ. 354 p.
Attribution
Fact Sheet prepared for NZPCN by P.J. de Lange 14 April 2007: Description adapted from Moore and Edgar (1970).
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Pterostylis irsoniana Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/pterostylis-irsoniana/ (Date website was queried)