Interest in the thermal acclimation of photosynthesis has been stimulated by the increasing relevance of climate change. However, little is known about intra-specific variations in thermal acclimation and its potential for breeding. In a recent study published in AoB PLANTS, Zaka et al. analysed intra-specific variations in the thermal acclimation of photosynthesis in a perennial herbaceous crop (alfalfa β Medicago sativa) by comparing cultivars from contrasting origins grown under a range of temperatures. It was concluded that both temperate and Mediterranean cultivars display strong patterns of thermal acclimation in the 5β40Β°C range. There was no evidence of superior performance by Mediterranean genotypes at high temperatures.