Tarengo Leek Orchid (Prasophyllum petilum)
In the ACT, the Tarengo Leek Orchid (Prasophyllum petilum) is only known to occur at the Hall Cemetery, but is also found in some grassy woodlands and grasslands of the Southern Tablelands and Western Slopes of NSW.
This lovely little orchid was declared an endangered species in 1996 under the Nature Conservation Act 1980 and also has special protection status in the ACT. It is listed as endangered nationally and in NSW.
The Tarengo Leek Orchid is a slender terrestrial orchid that grows to 30 centimetres. It flowers from October to November, producing 5 to 18 flowers. Because the leaves and flowers are both dull green, with pink tinges on the flowers, it’s hard to spot them among the grasses they grow amongst.
Between zero and 100 plants flower each year at the Hall Cemetery. Plants don’t usually flower in consecutive years - and sometimes not for 16 years - but do appear to flower every five years or so. We don't yet know the conditions needed to produce viable seeds so we can’t yet help increase numbers of plants.
Conservation threats
The major threat to the Tarengo Leek Orchid in the ACT is its restricted range and population. This leaves the plants in the ACT vulnerable to extinction from a single event. The distance between populations limits genetic diversity and makes the orchid vulnerable to environmental change and disease. Habitat loss is likely as new graves are established at the Hall Cemetery.
For many years a flock of Sulphur-Crested Cockatoos have repeatedly visited the Cemetery to feed during spring. They often cause damage to Tarengo Leek Orchid flowering stems by biting through the stems.
Competition from both native and exotic species is also a risk. Patches of the Hall Cemetery are dominated by exotic grasses that are feared to be overcrowding individual plants.
Climate appears to influence flowering, with winter nights at or below -4oC leading to fewer plants flowering the next year. The extent that climate change may influence the species remains unknown.
Conservation objectives
- Protect sites where the species is known to occur in the ACT from unintended impacts; including the implementation of suitable buffers around habitat to safeguard against any negative impacts from potential future re-zoning or development.
- Manage the species and its habitat to maintain the potential for evolutionary development in the wild.
- Improve the long-term viability of populations through management of adjacent woodland to increase habitat area and connect sub-populations.
- Expand the range of the Tarengo Leek Orchid in the ACT by providing suitable habitat and establishing new populations by translocation (upon advice from feasibility studies).
- Improve the understanding of the species’ ecology, habitat and threats.
- Strengthen stakeholder and community collaboration in the conservation of the species.
Conservation actions
The confined distribution and small population of the Tarengo Leek Orchid in the ACT places the species at high risk of local extinction. The conservation actions focus on maintaining the condition of the site and reducing the risk of disturbance.
Canberra Public Cemeteries Trust and Conservation Research oversee the management of the species and are guided by the Hall Cemetery Management Plan (Conservation Research and Canberra Cemeteries 2013), which includes actions associated with mowing, vehicle access, grave digging, cockatoo disturbance, fire and grazing.
The key conservation actions of the action plan are to:
- protect the population from impacts of recreation, infrastructure works and other damaging activities and unintended impacts
- to require site management to conserve the species
- monitor populations and the effects of management actions
- manage the grassland/woodland next to the cemetery to increase the habitat area or habitat connectivity
- undertake research and trials to increase the population size or establish new populations
- promote a greater awareness of, and strengthen stakeholder and community engagement in, the conservation of the species.
More information
Contact
Email environment@act.gov.au or phone Access Canberra on 13 22 81.