Astrebla is a small genus of xerophytic (adapted to survive in an environment with little liquid water) grasses found only in Australia. They are the dominant grass across much of the continent. They are commonly known as Mitchell grass after Scottish explorer Thomas Mitchell (1792-1855), who first collected a specimen near Bourke in New South Wales. Mitchell grasses grow on clay soils, mainly between an upper limit of 600 mm and a lower limit of 200 mm average annual rainfall, and at even lower rainfall in depressions where the water concentrates following rains, for example in Sturt's Stony Desert. Mitchell grasses are deep-rooted and become dormant during drought, allowing them to survive extended periods without rainfall. They are commonly found clumped together and reaching one metre high, providing habitat for organisms such as mammals.