Microtis oligantha
Common names
small onion orchid
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Orchids
Simplified description
This green orchid rarely grows more than 150mm tall when flowering and can be very hard to see when it grows amongst other grassland vegetation. It is distinguishable from the other Microtis species by having a dorsal sepal with an obtuse, rather than acute, tip that is not upturned. From above, the dorsal sepal also often appears opaque. In addition, it has a squarish labellum and usually fewer than 10 flowers on a scape, all characteristics which help distinguish it from the other onion orchid species.
Flower colours
Green
Detailed description
Terrestrial, glabrous, fleshy, tuberous bright green to dark green perennial herb forming small colonies or occurring as solitary plants. Plants at flowering up to 150 mm tall. Tubers globose to ovoid. Stem erect, terete, fleshy. Leaf solitary, usually overtopping inflorescence (but often damaged and so falling short), bright green to dark green, rarely tinged with red near base, closely sheathing stem for much of length, linear-terete, hollow, up to 200 mm long. Inflorescence a loose raceme up to 30 × 5 mm. Flowers 1–10, up to 2.8 mm diameter, shortly-stalked mostly widely spaced. Perianth green, segments up to 1.8 mm long, widely spreading, thick and fleshy. Dorsal sepal 2.5 mm long, broadly ovate, erect or projecting forwards, cucullate, concave, column-embracing, apex and margins rounded (without recurved apex), smaller than ovary at flowering. Lateral sepals much shorter, narrower, mostly acute to subacute, strongly deflexed, apices straight. Petals shorter again, broadly to narrowly obtuse, erect, mostly hidden under dorsal sepal. Labellum sessile, up to 2.0 mm long, green or yellow-green, oblong, slightly narrowed at mid-length; apex bluntly truncate rarely slightly emarginate, not apiculate; margin papillose, shallowly crenate, often thickened, rarely undulate; anterior callus variously developed, verrucose, rather irregular, often raised on a rounded ridge; basal calli conspicuous, dark green, tabular-ovoid to tabular, usually continuous at sides with narrow band of callus behind a transverse, slit-like (not pouched) furrow; labellum sharply deflexed, pendulous aligned more or less parallel to the ovary. Column short, obtuse, base of column mostly broader than stigma, wings mostly membranous throughout. Anther terminal, erect, situated above stigma, hemispherical, pollinia spheroidal, pollen granular. Stigma broadly ovate; rostellum ovate Capsules broadly ovoid, ovoid-ellipsoid, brown when ripe.
Similar taxa
Usually smaller than the other species of Microtis and with fewer flowers (up to 10). This species is best recognised by the obtuse rather than acute dorsal sepal whose apex is not upturned, and by the short-oblong to almost quadrate labellum with only shallowly crenate or rarely undulate margins. The labellum calli are indistinct and tabular.
Distribution
Endemic. New Zealand: North Island, South Island, Chatham Islands.
Habitat
Damp places in tussock grassland, on lake, tarn, river and wetland margins. Coastal to subalpine. Mainly montane to subalpine in the North Island, descending to sea level in the South and Chatham Islands
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
Family
Synonyms
None (first described in 1967)
Taxonomic notes
Chatham Island plants tend to be much larger than those seen on the other New Zealand islands.
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
December–March
Fruiting
March–May
Propagation technique
Easily grown in a damp sunny position. Should not be removed from the wild.
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]
FAC: Facultative
Commonly occurs as either a hydrophyte or non-hydrophyte (non-wetlands).
Other information
Plant of the Month
This plant has been featured as a Plant of the Month – see Trilepidea: NZPCN newsletter for February 2025 for the full story.
Etymology
microtis: Tiny eared
oligantha: Few-flowered
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.
MICOLI
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
Regional conservation statuses
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Regional conservation status of indigenous vascular plants in Otago” Jarvie S et al. (2024) report.
Otago: 2024 | Regionally Not Threatened
Referencing and citations
References and further reading
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): Microtis oligantha Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/microtis-oligantha/ (Date website was queried)