Angus's Onion 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: Microtis angusii

Conservation status in NSW: Endangered

Commonwealth status: Endangered

Gazetted date: 06 Jun 1997

Profile last updated: 04 Mar 2024

Description

A terrestrial orchid. Microtis species are commonly called 'onion orchids'. This refers to the leaves which are cylindrical like those of plants of the onion family. Grows to 25 - 60 cm tall with green, linear cylindrical and tapering leaves from 40 - 140 cm long and 4 - 8 mm wide. The leaves are usually much longer than the flowering stem which emerges from the leaf at about 12 - 20 cm above the soil. The flowering stem is 8 - 18 cm long and bears 20 - 60 small green flowers. Each flower is about 2.5 mm in diameter and bears a short, sharp but soft point, and is hood shaped. The flower is made up of two whorled sections, one within the other.

Distribution

All currently known records of the species are located within Northern Beaches LGA.

Collections thought to be Microtis unifolia (Common Onion Orchid) from other areas of NSW are genetically similar to Microtis angusii, and further genetic investigations are required to resolve taxonomic uncertainty around the species.

Habitat and ecology

All confirmed records of the species are from disturbed areas, with most individuals recorded in road verges.
The Ingleside population occurs on soils that have been modified but were originally those of the restricted ridgetop lateritic soils in the Duffys Forest - Terrey Hills - Ingleside and Belrose areas. These soils support a specific and distinct vegetation type, the Duffys Forest Vegetation Community which is listed as an endangered ecological community under the TSC Act and ranges from open forest to low open forest and rarely woodland.
Exists as subterranean tubers during most of the year. Produces leaves and then flowering stems in late winter and spring and flowers from May to October. By summer, the above ground parts have withered leaving no parts above ground.
Most Microtis species reproduce vegetatively by the formation of “daughter” tubers from the main tuber.

Regional distribution and habitat

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

Sydney Basin

Threats

As sites occur primarily in roadside areas, there is great potential for the population to be adversely affected by an inappropriate fire regime. The most likely scenario is too frequent fire caused by arson, hazard reduction activities and accidental sparking from cigarettes etc.
Uncontrolled site access has led to the degradation of sites in the past, particularly at the Ingleside site where the species was first identified. Rubbish dumping, soil compaction and soil dumping have led to habitat degradation at this location as well as construction of a sewerage pipe, use of the site as a fill dump, as a portaloo parking area and by the construction of a cement dam.
Weed species of concern at the known sites include Acacia saligna and Coolatai grass (Hyparrhenia hirta) as well as various exotic groundcover grasses and herbs.
Plants at the Mona Vale site have been grazed almost to the ground by rabbits and goats in the past. The goats have since been trapped, and Council has undertaken control of the rabbits. If grazing continues, the population may fail to flower and set seed for the season. The long term effect of grazing may be detrimental to the population. Rabbit browsing is a problem at many known sites.
As a rare orchid it is unfortunately a possible target for unscrupulous amateur orchid enthusiasts and professional orchid propagators. No level of unauthorised collection could be sustained by the population at this stage.
The species is susceptible to extinction via stochastic processes due to its small known population size and restricted distribution.
Potential for unsympathetic maintenance of the roadside - e.g. inappropriate chemical and/or physical weed control.
Mona Vale road is likely to be expanded in the near future, either removing habitat or intensifying effects of road proximity such as run-off or maintenance disturbance.

Recovery strategies

Priority actions are the specific, practical things that must be done to recover a threatened species, population or ecological community. The Office of Environment and Heritage has identified 14 priority actions to help recover the Angus's Onion Orchid in New South Wales.

Activities to assist this species

Determine and establish the most appropriate ex-situ storage of plant material.
Determine and undertake appropriate fire management of the known populations and possible habitat.
Prepare a weed assessment and management strategy for sites where it is known.
Undertake yearly monitoring at Ingleside during the flowering season (September - October).
Undertake surveys of potential areas during the flowering season (September - October).

Information sources

Bates, R. (1981) Observation of pollen vectors on a putative hybrid swarm of Microtis R.Br. Orchadian 7:14-15.
Bates, R. (1984) The genus Microtis R.B. (Orchidaceae): A Taxonomic revision with notes on biology. The Journal of the Adelaide Botanic Gardens.
Bates, R. (1986) The genus Microtis in Australia. Orchadian 8 (8): 163-166
Cady, L. and Rotherham, E.R. (1970) Australian Native Orchids in Colour. Reed, Frenches Forest.
Jones, D.L. (1975) The pollination of Microtis parviflora R.Br. Annals of Botany 39:585-589.
Jones, D.L. (1996) Microtis angusii, a new species of Orchidaceae from Australia. Orchadian 12 (1):10-12
NSW Scientific Committee (1997) Microtis angusii (a terrestrial orchid). Endangered species determination - final. DEC (NSW), Sydney.
Peakall, R. and Beattie A.J. (1989) Pollination of the orchid Microtis parviflora R.Br. by flightless worker ants. Functional Biology 3:515-522.
Peakall, R. and Beattie A.J. (1991) The genetic consequences of worker ant pollination in a self-compatible, clonal orchid. Evolution 45(8):1873-1848.
Weston, P.H. (1993) Orchidaceae. In: Harden, G.J. (ed.) Flora of NSW Volume 4. New South Wales University Press, Kensington.