Australian Desert Heath

Heaths are rare in the arid zone but can be found, for example, in parts of the Great Victoria Desert. They occur on the flanks and lower slopes of dunes, where it sometimes replaces the more typical hummock grass of Plectrachne and Triodia. They can grow to heights of about 30 cm and here they are dominated by Thryptomene maisonneuvii. Associated species include Calytrix longiflora and the endemic or near endemic Micromyrtus flaviflora (Myrtaceae). On the summits of dunes, heaths becomes more sparse and taller species occur such as Acacia salicina, Crotalaria cunninghamii, Gyrostemon ramulosus together with endemic or near endemic taxa like Callitris preissii subsp. verrucosa (Cupressaceae), Eucalyptus gongylocarpa (Myrtaceae) and Grevillea stenobotrya (Proteaceae).

Australian Astrebla Desert Grassland

Grass of the genus Astrebla is largely endemic to the arid and semi-arid zones of Australia. Four Astrebla grassland alliances have been identified based on the dominance of A. clymoides, A. lappaceae, A. pectinata or A. squarrosa. However, these often intergrade and have many associated species in common. Astrebla squarrosa is the most abundant species on the Carpentaria plains where it intergrades with Dichanthium grassland. It is also the tallest species reaching heights of up to 2 m. Other species rarely exceed 1 m. Astrebla lappaceae is probably the most common species overall extending over large areas, while A. pectinata is only dominant in the wetter areas. Astrebla elymoides is possible the least common, but sometimes forms monospecific stands in A. pectinata grassland. Associated species vary, but it is reckoned up to 100 species can be found in association with A. lappaceae. Among the many associated grasses are Aristida latifolia, Eriachne nervosa, Panicum decomposition and the endemic or near endemic Eragrostis xerophila and Spathia nervosa (Poaceae).

Australian Eragrostis Desert Grassland

These grasslands can be broadly divided in to three communities dominated by Eragrostis dielsii or E. setifolia or the endemic E. xerophila (Poaceae). The latter dominates tussock grassland on clay in the arid zone from western Queensland through Central Australia and westwards to the Indian Ocean. In central areas, it is associated with Astrebla pectinata, while on the western coastal plains species such as Chloris ruderalis, Dichanthium humilis, Enneapogon planifolius, Eragrostis lacunaria, Sporobolus actinocladus and Triraphis mollis are common associates. The occasional tree may include the endemic or near endemic Melaleuca lasiandra (Myrtaceae). Eragrostis dielsii is usually only dominant in waterlogged areas and E. setifolia is typically dominant on shallow soils on limestone. The later is abundant throughout the arid zone and extends on to the Nullarbor Plain.

Australian Plectrachne schinzii Spinifex Desert Grassland

Grassland dominated by the endemic Plectrachne schinzii (Poaceae) extends over vast tracts from the northwest through the Great Sandy Desert and into Central Australia. It is often associated with Triodia basedowii and T. pungens together with other grasses such as Danthonia bipartita and Eragrostis eropoda. Shrubs or small trees, such as the endemic or near endemic Acacia inaequilatera (Fabaceae) and Hakea macrocarpa (Proteaceae), are often scattered throughout these grasslands and should possibly, therefore, be described as savanna.

Australian Triodia Spinifex Desert Grassland

Four Triodia dominated grasslands have been identified. The dominant species are T. basedowii, T. irritans, T. mitchellii and T. pungens. The latter occurs across the arid interior from western Queensland to the Indian Ocean. In addition to a number of other grasses, associated species may include a number of endemic forbs such as the Euphorbia australis (Euphorbiaceae), and many annual species occur in the spaces between hummocks. Triodia basedowii often dominates hummock grasslands in the south. Again large numbers of associated annual species occur such as Calandrina balonensis, Cleome viscosa, Erodium crinitum, Euphorbia drummondii, Haloragis gossei, Lepidium rotundum, Podolepis canscens and the endemic or near endemic Euphorbia eremophila (Euphorbiaceae), Plychosema trifoliatum (family?) and Trachymene glaucifolia (Apiaceae). Triodia irritans is often found associted with the endemic Triodia scariosa (Poaceae) and occurs mainly in the south with possibly the largest stands occurring in the Musgrave Ranges in South Australia, while Triodia mitchellii is confined to semi-arid areas of Queensland and northern New South Wales.

Australian Zygochloa paradoxa Desert Grassland

Hummock grassland dominated by the endemic Zygochloa paradoxa (Poaceae) is centred on the Simpson Desert where it is mainly confined to the crests of sand dunes. The hummocks are often spaced at distances of 2-6 m apart. Associated herbaceous flora is entirely ephemeral with species such as Aristida arenaria, Citrullus lanatus, Crotalaria dissitiflora, Myriocephalus stuartii, Salsola kali, Tribulus hystrix, Tetrogonia expansa, Trichinium alopecuroideum, Trichodesma zeylanicum, Zygophyllum howittii and the endemic Blennodia pterosperma (Brassicaceae).


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