Australia is renowned for being the driest inhabited continent on Earth and ‘a land of droughts and flooding rains’ (Dorothea Mackellar). Over one-third of Australia’s land area can be considered ‘arid’ and a further third ‘semi-arid’ ( Martin 2006 ). Importantly, these areas are characterised not just by extended periods of low rainfall but also extremely patchy and unpredictable rainfall that sometimes produces enormous floods, driving some of the most expansive and dynamic riverine landscapes in Australia and the world. Inland Australia hasn’t always been arid, and for much of the Palaeocene supported lush rainforests and swamps of both angiosperms and gymnosperms. Gradual drying, with some wetter periods, has since occurred over a period of around 15 million years. A constantly changing climate throughout the Pleistocene, with glacial and inter-glacial cycling tending towards current levels of aridity, led to fluctuations in the distribution and abundance of many biological populations between periods of expansions and phases of contraction into refuges, which gradually favoured more adaptable taxa ( Martin 2006 ). Palaeo-botanical studies indicate that many of Australia’s arid zone species developed well before aridity took hold in central Australia and may have grown in these landscapes when still occupied by rainforest ( Martin 2006 ). The current flora therefore largely comprises relict taxa able to cope with these climatic changes together with a few species that have evolved specific adaptations in response to arid conditions ( Carolin 1982 ; Byrne et al . 2008 ).