Insights into trait-environment associations of communities and lineages: the case of dumbbell and kidney-shaped stomata

Stomata are the valves controlling the exchange of carbon dioxide and water vapor between plants and the atmosphere, and their evolution played a crucial role in enabling the colonization of terrestrial habitats and formation of terrestrial ecosystems 1. Stomata are made up of pairs of guard cells, which are kidney-shaped in most plants, and dumbbell-shaped in grasses, and flanked by specialized subsidiary cells. Several studies among small, diverse species showed that the opening and closing processes of these stomatal types differ.