Plants need to create a connection between the outside air and the plant or leaf interior, so that CO2 can reach the photosynthesis apparatus via diffusion. This is made possible through controllable micropores in the leaves, the stomata. At the same time, however, water vapor escapes from the leaves (transpiration) and water absorption via the roots becomes necessary. Photosynthesis, transpiration, water absorption and water transport are thus closely linked with each other and with the atmosphere. For the evolution of land plants these processes are of great importance, also with regard to the influence of climate and atmosphere. Functional morphological and paleoecological research are being conducted on this topic which is integrated in cross-cutting issue Q4. Additionally, biomimetic projects are conducted within the context of "Free Research Fields".