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Species profile—Thesium australe (toadflax)


Plantae (plants) → Equisetopsida (land plants) → SantalaceaeThesium australe (toadflax)

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Species details

Plantae (plants)
Equisetopsida (land plants)
Scientific name
Thesium australe R.Br.
Common name
WildNet taxon ID
Alternate name(s)
austral toadflax
Nature Conservation Act 1992 (NCA) status
Environment Protection and Biodiversity Conservation Act 1999 (EPBC) status
Conservation significant
Pest status
Thesium australe is a short-lived erect herb with wiry stems up to 40 cm high. It is parasitic on the roots of other plants, particularly kangaroo grass (Themeda triandra). The leaves are arranged alternately on the stem and are narrow and linear in shape, the apex is acute and the base is cuneate (narrowly triangular), 0.5 to 5 cm by 0.05 to 0.15 cm; the petiole is up to 1 mm long; . The flowers have 2 narrow bracts (leaf-like structures) at the base; they are solitary, and arise from the axils on a peduncle 1 to 2 mm long that is subtended by a leaf. The perianth is 2 to 3 mm long, with 5 lobes which are white in colour. The fruit is an oval or globular nut that is 2 to 2.5 mm long. The nut has 8 to 10 longitudinal ribs and a network of veins that run over the surface. (Ross, 1984; DSEWPC, 2012).
Thesium australe is the only species of Thesium occurring in Australia (Ross, 1984).
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Thesium australe is found in south east Queensland from Bundaberg to Dalby and to the NSW border, and also found west in Carnarvon NP. The species also occurs in NSW and Victoria, it is presumed to be extinct in Tasmania (DSEWPC, 2012).
Distributional limits
-24.927595, 147.9605701
-28.2484079, 153.5010596
Range derivation
Range derived from extent of the taxon's verified records
Thesium australe grows in grassland or woodland, often in damp sites. Examples of associated vegetation includes: open woodland with Eucalyptus tereticornis and E. tindaliae on skeletal soils; on heavy alluvium soil in grassy E. populnea woodland; on black cracking clay in grassland of Dichanthium sericeum; and grassland dominated by Themeda triandra and Heteropogon contortus on basaltic, rocky soils (Queensland Herbarium, 2012).
Thesium australe flowers from October through to April (Queensland Herbarium, 2012).
Threatening processes
The contraction in the documented range of Thesium australe is due to heavy grazing and cultivation of grasslands and grassy woodlands in the lowlands of Victoria. Changes in fire regime may also be responsible for the absence of Thesium australe from the native grassland remnants of the lowland plains (Scarlett and Parsons, 1982). The absence of Thesium australe from areas with dense shrub and/or tree cover at known sites suggests that the maintenance of open conditions by frequent firing in the long-term may be as important for the survival of Thesium australe as the apparent stimulation of germination by fire mentioned above. In its final recommendations, the Scientific Advisory Committee (SAC 1991) determined that the Thesium australe is: in a demonstrable state of decline which is likely to lead to extinction; and significantly prone to future threats which are likely to lead to extinction (DSEWPC, 2012)
Status notes
Listed as Vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 and Vulnerable under the Queensland Nature Conservation Act 1992
Occurs in the following Queensland pastoral districts: Darling Downs, Leichhardt, Moreton, Wide Bay. Also occurs in the following regions: New South Wales, Victoria.
Department of Sustainability, Environment, Water, Population and Communities (DSEWPC) (2012). Thesium australe in Species Profile and Threats Database, Department of Sustainability, Environment, Water, Population and Communities, Canberra.
Queensland Herbarium (2012). Specimen label information. Queensland Herbarium. Accessed 11/01/2012.
Ross, E.M. in Stanley, T.D. and Ross, E.M. (1984). Flora of South-eastern Queensland 1: 69, 71, .
Scarlett, N.H. and Parsons, R.F. (1982). Rare plants of the Victorian plains. In: Species at risk: research in Australia (Groves, R.H. and Ride, W.D.L., eds). Australian Academy of Science, Canberra.
Profile author
Ronald Booth (22/03/2012)

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Data source

This profile data is sourced from the QLD Wildlife Data API using the Get species by ID function used under CC-By 4.0.

This information is sourced from the WildNet database managed by the Queensland Department of Environment and Science.

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Last updated
20 May 2024