Greenhood Orchid - profile

Indicative distribution

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Key:

known

predicted

The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.

Scientific name: Pterostylis cobarensis

Conservation status in NSW: Vulnerable

Commonwealth status: Not listed

Profile last updated: 01 Nov 2022

Description

Terrestrial orchid with 7-11, narrow-elliptic leaves forming a basal rosette, each 1.5-2.5 cm long and 5-8 mm wide. Flowers 3-8 on stems to 40 cm high, with 3-5 closely sheathing stem leaves. The flowers are transparent with brown and green markings, each flower about 1.2 cm long.

Distribution

Recorded from Bourke, Nyngan, Cobar, Nymagee, Warren, Gilgandra, Narrabri, Coonabarabran districts. Recorded from a number of reserves and state forests including Mutawintji, Gundabooka, Culgoa, Warrumbungles National Parks, Quanda, Yathong Nature Reserves, Mt Grenfell Historic Site and Bimbilwindi and Pilliga East State Forests. There are also records from the Darling Downs district of Queensland.

Habitat and ecology

Habitats are eucalypt woodlands, open mallee or Callitris shrublands on low stony ridges and slopes in skeletal sandy-loam soils.
Associated species include Eucalyptus morrisii, E. viridis, E. intertexta, E. vicina, Callitris glaucophylla, Geijera parviflora, Casuarina cristata, Acacia doratoxylon, Senna spp. and Eremophila spp.
Flowers from September to November. Vegetative reproduction is not common in this group of Greenhoods, but some species may form more than one dropper annually. Plants are deciduous and die back to the large, underground tubers after seed release. New rosettes are produced following soaking autumn and winter rains.
Pollinated by the males of small gnats which are attracted to the flower by some pseudosexual perfume.
The group includes some of the most drought tolerant orchids in Australia. Survival strategies include the large tuberoids which store moisture, the overlapping rosette leaves which trap moisture and direct it to the root zone, and the tendency to grow in sites of litter accumulation and near rocks where run-off is concentrated.
Pterostylis cobarensis occurs as frequent to abundant plants (sometimes occasional) in usually very localised populations.
Within the Macquarie River valley, Pterostylis cobarensis only recorded from igneous rock outcrops with habitat of Eucalyptus dwyeri - Alstonia constricta open woodland. No records have been made from the surrounding alluvial soil floodplains, just on shallow sandy-loam on rock outcrops.
Annual monitoring of a rocky hill within the Macquarie Valley north of Warren has only recorded orchid emergence twice in six years between 2016-2021, with both occasions having significantly above-average rainfall in the season prior to monitoring in October. This period included four consecutive years of no orchid emergence.
With regards to the Macquarie River valley sites, while the species can be found in more exposed sites on rocky hills, the majority of plants are located at the bases of larger rock shelves or in crevises between rocks that provide shelter and water accumulation.
Annual monitoring of one population in the Macquarie River valley near Warren has recorded the number of flowers per stem to vary from 1-5, with the most frequent being 2-3.

Regional distribution and habitat

Click on a region below to view detailed distribution, habitat and vegetation information.

Threats

Feral goats, rabbits and pigs (grazing, browsing and erosion). Rabbits have been known to dig up the tubers
Habitat degradation (the granite ridge and rocky slope habitats are particularly vulnerable to the detrimental impacts of feral goats).
Weed infestation and competition (may limit the species).
Climate change as these orchids grow on the arid extreme of known range for orchid species. If the western areas become drier the range of this species may be restricted to the east
Lack of information on species locations and population sizes
Disturbance by feral pigs
Disturbance associated with overgrazing (grazing/trampling by stock during flowering period is detrimental, ground compaction above tubers in dormant period may be a problem in high stock travel/rest areas).
Weed infestation and competition which degrade the vegetation community.
Clearing of habitat for agriculture.
Need to understand the viability of seed and the relationship with symbiotic fungi, particularly from populations at limits of east - west distribution. Need to collect seed from all known populations for storage at Mt Annan Botanical Gardens.

Recovery strategies

A targeted strategy for managing this species has been developed under the Saving Our Species program; click here for details. For more information on the Saving Our Species program click here

Activities to assist this species

Control feral goat population.
Protect populations from feral goats through fencing.
Weed control programs.
Weed monitoring in population areas.
No further loss of extant populations.
Report any new populations to the Department of Planning, Industry and Environment.

Information sources

Bishop, T. (2000) Field Guide to the Orchids of New South Wales and Victoria. (New South Wales University Press, Sydney)
Briggs, J.D. and Leigh, J.H. (1996) Rare or Threatened Australian Plants. Revised Edition. (CSIRO Publishing, Melbourne)
Clements, M.A. (1989) Catalogue of Australian Orchidaceae. Australian Orchid Research 1: 1-160.
Jones, D.L. (1988) Native Orchids of Australia. Reed, Sydney.
Jones, D.L. (1994) Pterostylis. In Harden, G.J. (ed.) Flora of New South Wales. Volume 4. New South Wales University Press: Sydney.
Norris, E.H. and Thomas, J. (1991) Vegetation on rocky outcrops and ranges in central and south-western New South Wales. Cunninghamia 2(3): 411-441.
Pressey, R.L., Cohn, J.S. and Porter, J.L. (1990) Vascular plants with restricted distributions in the Western Division of New South Wales. Proceedings of the Linnean Society of New South Wales 112: 213-227
Quality Environmental Management Pty Ltd (1994) Conservation Research Statement and Species Recovery Plan - Pterostylis gibbosa. Australian Nature Conservation Agency Endangered Species Program Project No. 250 NPWS, Sydney

IBRA Bioregion	IBRA Subregion	Known or predicted	Geographic restrictions region

Brigalow Belt South	Pilliga	Known	None
Brigalow Belt South	Pilliga Outwash	Known	None
Broken Hill Complex	Mootwingee Downs	Known	None
Cobar Peneplain	Barnato Downs	Known	None
Cobar Peneplain	Canbelego Downs	Known	None
Cobar Peneplain	Nymagee	Known	None
Darling Riverine Plains	Bogan-Macquarie	Known	None
Mulga Lands	Nebine Plains	Known	None
Murray Darling Depression	South Olary Plain	Known	None