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: Prasophyllum petilum
Profile last updated:
31 Jul 2015
Tarengo Leek Orchid reaches to 35 cm tall. This species can be distinguished from the more common onion orchids (Microtis spp.) that grow in its habitat by the pinkish-purple base to the leaf. Each plant produces a solitary, tubular, fleshy, dull green leaf, growing to 35 cm tall. The flower-spike emerges in mid spring to early summer from a hole near the base of the leaf. The spike, reaching to 12 cm tall, has about 20 fragrant flowers with pointed petals. The flowers are usually a pale whitish-green, but can be pink or pale purple. Plants can be very cryptic when growing in small numbers and within tall grasses.
Natural populations are known from a total of five sites in NSW. These area at Boorowa, Captains Flat, Ilford, Delegate and a newly recognised population c.10 k SE of Muswellbrook. It also occurs at Hall in the Australian Capital Territory. This species has also been recorded at Bowning Cemetery where it was experimentally introduced, though it is not known whether this population has persisted.
Habitat and ecology
- Grows in open sites within Natural Temperate Grassland at the Boorowa and Delegate sites.
- Also grows in grassy woodland in association with River Tussock Poa labillardieri, Black Gum Eucalyptus aggregata and tea-trees Leptospermum spp. at Captains Flat and within the grassy groundlayer dominated by Kanagroo Grass under Box-Gum Woodland at Ilford (and Hall, ACT).
- Apparently highly susceptible to grazing, being retained only at little-grazed travelling stock reserves (Boorowa & Delegate) and in cemeteries (Captains Flat, Ilford and Hall).
- Flowers in October at Boorowa and Ilford, and December at Captains Flat and Delegate.
- Population density at the Boorowa site is higher in the open grassland dominated by wallaby grasses Austrodanthonia spp., compared to that within the denser stands of Kangaroo Grass Themeda australis.
- Highly colonial, with very large numbers present and very conspicuous at the Boorowa site, but cryptic at the Captains Flat, Ilford and Delegate sites where low numbers are recorded. The population near Muswellbrook is also small.
- Flowers are followed by fleshy seed capsules in summer.
- Plants retreat into subterranean tubers after fruiting, so are not visible above-ground.
Regional distribution and habitat
Click on a region below to view detailed distribution, habitat and vegetation information.
- Previous threats appear to have been loss, degradation and fragmentation of habitat and populations to residential, infrastructure and agricultural developments.
- Current threats are inappropriate mowing or grazing regimes, especially in spring and summer when above-ground parts are present.
- Threatened by competition from other plant species, both native (e.g. Kangaroo Grass, tea- trees) and non-native (e.g. Sweet Vernal-grass Anthoxanthum odoratum).
- Particularly vulnerable to chance extinctions because so few populations exist.
- Encroachment of herbaceous perennial weeds such as St Johns Wort and Pattersons curse competing for space and resources.
- Current or potential future land management practices do not support conservation
- Road widening and other development pressures at the population at Muswellbrook
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
- Protect known populations from changes to land use.
- Do not allow grazing, mowing or other disturbances when above-ground parts are present.
- Establish the most effective means of control or management of competing species.
- Monitor the known populations to ensure that management is retaining populations.
- Mark sites and potential habitat onto maps (of the farm, shire, region, etc) used for planning (e.g. road works, residential and infrastructure developments, remnant protection, rehabilitation).
- Search for new populations in potential habitat between the known sites.
- ACT Government (1997) A leek orchid (Prasophyllum petilum): an endangered species. Action Plan No.4. Environment ACT.
- Bishop, T. (2000) Field Guide to the Orchids of New South Wales and Victoria. (New South Wales University Press, Sydney)
- Eddy, D. (2002) Managing Native Grassland: a guide to management for conservation, production and landscape protection. (World Wide Fund for Nature Australia, Sydney)
- Eddy, D., Mallinson, D., Rehwinkel, R and Sharp. S. (1998) Grassland Flora: a field guide for the Southern Tablelands (NSW & ACT). (Environment ACT, NSW National Parks and Wildlife Service, World Wide Fund for Nature Australia, Australian National Botanic Gardens, Natural Heritage Trust, Canberra)
- Harden, G.J. (ed.) (1993) Flora of New South Wales Vol. 4. UNSW Press, Kensington, NSW.
- NSW National Parks and Wildlife Service (2003) Draft Recovery Plan for the Tarengo Leek Orchid (Prasophyllum petilum). NSW NPWS, Sydney.
Known or predicted
Geographic restrictions region