Illawarra Greenhood - 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 gibbosa

Conservation status in NSW: Endangered

Commonwealth status: Endangered

Profile last updated: 23 Jan 2024

Description

Pterostylis - the greenhoods - is a large genus of ground-dwelling orchids with mostly green flowers. The Illawarra Greenhood has a rosette of rounded leaves at the base of the stem, each to 35 mm long. In addition there are up to six leaves that sheath the flower stem, which may be 45 cm high and bear up to seven flowers. The flowers are bright glossy green with transparent patches in the hood. The very broad black labellum (‘lip’ petal) protrudes from the front of the flower.

Distribution

Known from a small number of populations in the Hunter region (Milbrodale), the Illawarra region (Albion Park and Yallah) and the Shoalhaven region (near Nowra). It is apparently extinct in western Sydney which is the area where it was first collected (1803).

Habitat and ecology

All known populations grow in open forest or woodland, on flat or gently sloping land with poor drainage.
In the Illawarra region, the species grows in woodland dominated by Forest Red Gum Eucalyptus tereticornis, Woollybutt E. longifolia and White Feather Honey-myrtle Melaleuca decora. Near Nowra, the species grows in an open forest of Spotted Gum Corymbia maculata, Forest Red Gum and Grey Ironbark E. paniculata. In the Hunter region, the species grows in open woodland dominated by Narrow-leaved Ironbark E. crebra, Forest Red Gum and Black Cypress Pine Callitris endlicheri.
The Illawarra Greenhood is a deciduous orchid that is only visible above the ground between late summer and spring, and only when soil moisture levels can sustain its growth. The leaf rosette grows from an underground tuber in late summer, followed by the flower stem in winter. After a spring flowering, the plant begins to die back and seed capsules form (if pollination has taken place).
As with many other greenhoods, male fungus gnats are believed to be the pollinator.
The Illawarra Greenhood can survive occasional burning and grazing because of its capacity to reshoot from an underground tuber.

Regional distribution and habitat

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

Sydney Basin

Threats

Further loss and fragmentation of habitat, particularly through clearing for agriculture and residential development.
Habitat degradation resulting from weed invasion particularly, Lantana and Asparagus fern; uncontrolled vehicular/pedestrian access to sites; and inappropriate fire regimes.
Small numbers and a limited distribution put the species at risk of extinction through natural catastrophes or environmental changes.
Habitat degradation and physical disturbance of the species due to recreational users, including mountain bikes.
Inappropriate fire regime including too-frequent fire due to arson.
Browsing and disturbance by native herbivores

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

Support and provide information to landholders regarding appropriate management,
Determine and apply appropriate fire management practices.
Install fencing/signage to control access.
Protect areas of known and potential habitat from clearing and further fragmentation
Restore degraded habitat using bush regeneration techniques.
Monitor the health of known populations.
Map known sites and conduct searches of potential habitat for new sites.

Information sources

Bishop, T. (2000) Field Guide to the Orchids of New South Wales and Victoria. (New South Wales University Press, Sydney)
Harden, G.J. (ed.) (1993) Flora of New South Wales Vol. 4. UNSW Press, Kensington, NSW.
NSW National Parks and Wildlife Service (2002) Pterostylis gibbosa (an orchid) Recovery Plan. NSW NPWS, Hurstville NSW.

IBRA Bioregion	IBRA Subregion	Known or predicted	Geographic restrictions region

Other State	Jervis Bay Territory	Predicted	None
Sydney Basin	Hunter	Known	None
Sydney Basin	Illawarra	Known	None
Sydney Basin	Jervis	Known	None
Sydney Basin	Yengo	Known	None

Images

Illawarra greenhood, Albion Park, NSW Image 1 of 6.
View slideshow.

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