The native perennial grasses Austrodanthonia spp. are widespread and of great agricultural economic importance to large areas of southern Australia. However, little is known of the adaptive genetic variation that exists within wild populations. Intra-specific genetic variation has significant implications for the restoration and management of native plant communities because different seed sources may exhibit differences in adaptation. Using two common garden studies, we measured variation in morphological traits (flowering and growth) and water-use efficiency (carbon-isotope discrimination ') of Austrodanthonia caespitosa (Gaudich.) H.P. Linder and related species (A. bipartita, A. eriantha, A. fulva and A. setacea) and related this variation to environmental characteristics. Most variation for all species occurred among populations suggesting ecotypic variation. The significant relationship between flowering and growth characteristics of A. caespitosa and both large-scale climatic variables such as spring rainfall and sunshine hours and small-scale site characteristics such as shading provides evidence for trait-dependent adaptation at different scales. While components of fecundity such as flowering time and number of inflorescences represent important fitness traits, for other traits such as intrinsic water use there were no significant differences between populations. We discuss the implication of these results to both growth characteristics and sourcing seed.