Understanding how species have adapted to climate changes in the past is vital for predicting their evolutionary potential in response to future changes. This study will delve into how evolutionary radiations in two dominant lineages in Brazilian rupestrian grasslands (canelas-de-ema and candombás, Velloziaceae) were influenced by distinct climatic shifts during their radiations. This resulted in adaptations to current conditions of extreme seasonality, poor soils, and temperature variation. We will employ phylogenomic analyses to investigate the evolutionary patterns of water use strategies. Furthermore, we aim to identify candidate genes associated with these strategies, which could potentially offset the anticipated decline in plant productivity due to current climate change. This research will also enable us to estimate the evolutionary potential of rupestrian grasslands in the face of climate change. The findings could provide significant insights because this environment is a natural evolutionary laboratory, boasting one of the planet’s most diverse and threatened floras.