Awn length variation in Australia’s most widespread grass, Themeda triandra, across its distribution

Themeda triandra (kangaroo grass) is the most widespread plant species in Australia. Using herbarium specimens, we quantified awn-length variation across its distribution in relation to climate. We found that awn lengths were shortest around the eastern and southern coast of Australia (with short awns also concentrated in the Pilbara), increasing in length progressively inland and towards the north. There was a significant positive relationship between awn length and mean annual temperature. Further research is needed to understand why awn lengths vary, and how awn-length variation affects seed and seedling fitness in natural habitats.