Sturt's Desert Rose is also known as the Darling River Rose, the Cotton Rosebush and Australian Cotton. It is the floral emblem of the Northern Territory and appears in stylised form on the official flag as well as 2c stamp (yes, they existed) from the 1970s.

This wild Australian species is from the genus Gossypium that includes common cotton, G. hirsutum. It belongs to the Hibiscus or Mallow family, Malvaceae which is widespread in tropical and temperate regions of the world.

The specific and varietal names (Gossypium sturtianum var. sturtianum) honour Australian explorer Captain Charles Sturt (1795-1869) who first collected the species ‘in the beds of the creeks on the Barrier Range’ during his journey to central Australia in 1844-45. The specimens were placed at (the) ‘disposal’ of the Scottish botanist, Robert Brown (1773-1858), who described the plant in 1849 and named it Sturtia Gossypioides. In Brown's opinion: ‘Sturtia is no doubt very nearly related to Gossypium’. In 1947 J.H. Willis of the National Herbarium of Victoria proposed the name by which it is currently known, Gossypium sturtianum var. sturtianum, to distinguish it from a second sub-species, G. sturtianum var. nandewarense, found only in north- eastern New South Wales (around Narrabri) and the Expedition Range in central Queensland. Gossypium sturtianum var. sturtianum is found in semi-arid to arid areas of most mainland states of Australia and in the Northern Territory.

Sturt’s Desert Rose has a life cycle of about 10 years, growing from 1–2 m tall and 1–2 m wide with dark green round-to-oval leaves usually with black stipples. Its elegant pink-mauve flowers have deep red bases forming a contrasting centre, although they vary widely in hue. Flowers can be seen for most of the year but peak in late winter, and senesce within a day or two of blooming. There is a small cotton spore in the centre of the flower.

Plants can be found on stony or rocky slopes, or in dry creek beds, around Alice Springs and throughout the northern savannah of Australia. They are drought-tolerant, being able to conserve and store water. Adaptations include few stomata which are protected and found on the underside of leaves to reduce transpiration. Also, they have internal water storage, reducing the need to rely on regular rainfall. These sources can be in the trunk or root system. Finally, deep root systems enable them to tap water from deep underground.

Distribution of Sturt’s Desert Rose Defences: G. sturtianum contains a substance common to many Gossypium species, namely gossypol. Gossypol is toxic to all non- ruminant animals such as camels minimising chances of predation.

Brian Atwell, Alison Downing, Kevin Downing Department of Biological Sciences 24th February 2014

Watercolour by E. E. Gostelow, from Flora of Broken Hill, Cartwright’s Creek, Summer, 1920.

Map: Modified from Australian Native Plants Society (Australia): http://asgap.org.au/g-stu.html