Plants are unique among multicellular organisms because much of their physiology is biophysical, rather than behavioral, and the anatomy that defines these biophysical capabilities is preserved in the fossil record. Mathematical models, when applied to fossilized plant organs—particularly leaves and stems—can provide quantitative insight into the physiology and ecology of plants that have been extinct for hundreds of millions of years. Comparing the physiology of extinct plants with strategies that are currently employed by living plants sheds light on ecophysiological trajectories in plant evolutionary history and the history of plant-environment coevolution.

In this presentation, I will describe the history of water transport in land plants and focus on key plants from the Euramerican Carboniferous tropical forests, including Medullosa, a morphologically diverse genus of Carboniferous plants that evolved fronds and stems capable of high rates of transpiration. Each of these plants contains anatomical features that result in novel physiologies, and together they represent the early evolution of physiological complexity—and the capability to influence regional climates and biogeochemical cycles—in terrestrial ecosystems.