Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Critically Endangered
Listing and Conservation Advices Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood) (Threatened Species Scientific Committee, 2001b) [Listing Advice].
 
Recovery Plan Decision Recovery Plan required, this species had a recovery plan in force at the time the legislation provided for the Minister to decide whether or not to have a recovery plan (19/2/2007).
 
Adopted/Made Recovery Plans Flora Recovery Plan: Tasmanian Threatened Orchids 2006-2010 (Threatened Species Section (TSS), 2006a) [Recovery Plan].
 
Policy Statements and Guidelines Draft survey guidelines for Australia's threatened orchids (Department of the Environment, 2013b) [Admin Guideline].
 
Federal Register of
    Legislative Instruments
Declaration under s178, s181, and s183 of the Environment Protection and Biodiversity Conservation Act 1999 - List of threatened species, List of threatened ecological communities and List of threatening processes (Commonwealth of Australia, 2000) [Legislative Instrument].
 
Inclusion of species in the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (05/10/2001) (Commonwealth of Australia, 2001c) [Legislative Instrument].
 
State Government
    Documents and Websites
TAS:Threatened Species Listing Statement-Midland greenhood Pterostylis commutata D. L. Jones 1994 (Tasmanian Department of Primary Industries, Parks, Water and Environment (TAS DIPWE), 2000j) [Information Sheet].
TAS:Pterostylis commutata (Midland Greenhood): Species Management Profile for Tasmania's Threatened Species Link (Threatened Species Section (TSS), 2014bg) [State Action Plan].
TAS:Flowering Times of Tasmanian Orchids: A Practical Guide for Field Botanists (Wapstra, M., N. Roberts, H. Wapstra & A. Wapstra, 2008) [Information Sheet].
State Listing Status
TAS: Listed as Endangered (Threatened Species Protection Act 1995 (Tasmania): September 2012 list)
Scientific name Pterostylis commutata [64535]
Family Orchidaceae:Orchidales:Liliopsida:Magnoliophyta:Plantae
Species author D.L.Jones
Infraspecies author  
Reference Muelleria 8(2): 187, fig. 3e-g (1994).
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

Scientific name: Pterostylis commutata

Common name: Midland Greenhood

A taxonomic review of Greenhoods has split Pterostylis into several new genera. The Midland Greenhood has been renamed Oligochaetochilus commutatus, however the change is not yet widely accepted and the species is still treated as belonging to the Pterostylis genera (Tas DIPWE 2000j).

The Midland Greenhood belong to a group of orchids characterised by the dorsal sepals and petals being united to form a green, hood-like structure that dominates the flower. The labellum has the interesting property that when triggered by touch it flips inwards towards the column. This traps any insect inside the flower and any struggle to escape aids pollination. Greenhoods are also deciduous terrestrials that have fleshy tubers, which are replaced annually. During the life cycle all greenhoods produce a rosette of leaves. The rosette of the Midland Greenhood encircles the base of the flower stem. The 6–10 rosette leaves are elliptical to narrowly oval shaped, 18–32 mm long and 5–8 mm wide. The rosette usually withers by flowering time (Jones et al. 1999). The Midland Greenhood flowers in December and January. Whilst in flower the plants are 12–22 cm tall and have 1–5 shiny green flowers with translucent markings on the hood. The hood apex curves down strongly and terminates with an apical point 15–20 mm long. The two lateral sepals are green with dark green lines and transparent areas. They hang down and are joined together leaving 25–30 mm at the tips. The labellum is dark green and also hangs down. The labellum has a turned up tip and an irregularly wavy margin with short white bristles. A further two white long bristles occur near the base. The flowers are 42–50 mm long and 6–8 mm wide (Tas DIPWE 2000j).

Due to the distinct flowers the Midland Greenhood is not readily confused with other orchid species (Tas DIPWE 2000j).

The Midland Greenhood occupies an area 75 km² near Tunbridge and Ross. Although its area of occupancy is large in relation to other Tasmanian orchids, in total the species occupies an area of 1 ha. The following important locations have been documented (Tas DIPWE 2000j):

  • private land, north of Tunbridge (17 plants, 0.5 ha)
  • Township Lagoon Nature Reserve (3 plants, 0.0001 ha)
  • Ross Cemetery and adjacent roadside and private land (10–20 plants, 0.25 ha)
  • private land north-east of Ross (6 plants, 0.05 ha)
  • private land south of Ross (6 plabts, 0.0002 ha).

The Midland Greenhood is found in native grassland and Eucalyptus pauciflora grassy woodland. It is found on well drained sandy soils and basalt loams and occurs in small, loose colonies. The species occurs in one of the driest regions of the state with an annual rainfall of less than 500 mm. It has adapted to the dry conditions by storing water in large tubers (Tas DIPWE 2000j).

The Midland Greenhood, like most Tasmanian orchids is threatened by land clearing for agricultural activities. Most populations occur on private land that is being used for agricultural purposes. The cropping of native pastures, as well as ploughing and fertilising (as orchids are sensitive to such activities) is likely to have casued the species distribution to become fragmented and reduced to small colonies. Extensive surveys of the Midlands basalt grasslands and grassy woodlands produced only one new population. Some sites are used for grazing and stock routes, however at least one private land owner has diverted a proposed stock route away from a colony of Midland Greenhoods (Tas DIPWE 2000j).

The colony at the Ross Cemetery has suffered from slashing at the wrong time. This has caused the loss of flowering plants and adversely impacted the reproduction cycle. The removal of ancient pines at the site has also caused the soils to dry out to such an extent that the plants have not produce rosettes. A colony of 10 plants at the cemetery is believed to have died due to weed spraying which the orchid was above ground. The Midland Greenhood has not been seen at another site opposite the cemetery. This site has become infested with gorse and has been heavily overgrazed in dry years. The small number of existing plants coupled with their sparse distribution makes them more susceptible to stochastic processes (Tas DIPWE 2000j).

The Flora Recovery Plan: Tasmanian Threatened Orchids 2006-2010 (TSS 2006a) was developed to address the threats facing 68 threatened orchid species in Tasmania. The overall objective of recovery is to minimise the probability of extinction in the wild of threatened orchid species listed on the Tasmanian TSP Act and the Commonwealth EPBC Act and to increase the probability of each taxon becoming self-sustaining in the long-term.

Within the life span of the plan (five years), the specific objectives for recovery for Tasmania's threatened orchids are:

  • Acquire accurate information for sound management decisions and conservation status assessments.
  • Ensure priority populations are managed appropriately and are securely protected.
  • Increase the number of known populations of threatened orchid taxa.
  • Raise public awareness of orchid conservation issues and develop mechanisms to encourage and coordinate community participation in orchid recovery programs.
  • Establish a network of government and non-government organisations and individuals that can provide input into recovery programs and undertake recovery actions.
  • Develop a better understanding of the life history and ecological requirements of threatened orchids in Tasmania.
  • Increase the size of priority populations in the wild.
  • Identify critical and potential habitat.
  • Establish a genetically representative ex situ collection of orchid taxa facing imminent extinction in the wild.

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood) (Threatened Species Scientific Committee, 2001b) [Listing Advice].
Agriculture and Aquaculture:Livestock Farming and Grazing:Grazing pressures and associated habitat changes Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood) (Threatened Species Scientific Committee, 2001b) [Listing Advice].
Ecosystem/Community Stresses:Indirect Ecosystem Effects:Restricted geographical distribution (area of occupancy and extent of occurrence) Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood) (Threatened Species Scientific Committee, 2001b) [Listing Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Competition and/or habitat degradation by weeds Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood) (Threatened Species Scientific Committee, 2001b) [Listing Advice].
Species Stresses:Indirect Species Effects:Low numbers of individuals The Orchids of Tasmania (Jones, D.L., H. Wapstra, P. Tonelli & S. Harris, 1999) [Book].
Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood) (Threatened Species Scientific Committee, 2001b) [Listing Advice].

Jones, D.L., H. Wapstra, P. Tonelli & S. Harris (1999). The Orchids of Tasmania. Carlton South, Victoria: Melbourne University Press.

Tasmanian Department of Primary Industries, Parks, Water and Environment (TAS DIPWE) (2000j). Threatened Species Listing Statement-Midland greenhood Pterostylis commutata D. L. Jones 1994. [Online]. Available from: http://www.dpiw.tas.gov.au/inter.nsf/Attachments/SROS-6VJ7GP/$FILE/Pterostylis%20commutata%20listing%20statement.pdf.

Threatened Species Scientific Committee (2001b). Commonwealth Listing Advice on Pterostylis commutata (Midland Greenhood). [Online]. Available from: http://www.environment.gov.au/biodiversity/threatened/species/p-commutata.html.

Threatened Species Section (TSS) (2006a). Flora Recovery Plan: Tasmanian Threatened Orchids 2006-2010. [Online]. Hobart, Tasmania: DPIWE. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tasmanian-orchid.html.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Pterostylis commutata in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Sun, 21 Sep 2014 14:08:38 +1000.