Seed yield and dormancy status are key components of species fitness that are influenced by the maternal environment. Huang et al. grow the Arabidopsis thaliana ecotype Burren (Bur), which is adapted to a cool, damp climate, under conditions normally experienced by the Cape Verdi Isle (Cvi) ecotype, which is adapted to a hot, dry climate. They find that viability of pollen is unaffected, but limited filament extension relative to that of the pistils results in failure to pollinate. Both seed yield and dormancy are reduced, suggesting that higher temperatures predicted in climate change scenarios will impact on the seed performance of the cool-adapted ecotype.