Seminars & Colloquia

Leaf Veins and Pollen Grains: Robustness, Optimization and Design Principles in the Plant Kingdom

Eleni Katifori, Rockefeller University/Physics & Mathematical Biology

Throughout their evolutionary history, plants have evolved a variety of adaptations to better control hydration levels and transfer water to the parts of the organism as needed. These adaptations frequently directly reflect physical principles that dictate plant physiology. In this talk we consider two such examples, pollen grains and leaf venation. Upon release from the anther, pollen grains of angiosperm flowers dehydrate. To survive this process, the pollen wall folds onto itself to prevent further desiccation. Here, we model the pollen wall as a closed thin shell of varying mechanical properties and demonstrate that simple geometrical and mechanical principles are sufficient to predict the folded shape and identify the basic design requirements for reversible deformation. The morphology of leaf veins is similarly tightly constrained by water delivery demands across the surface of the leaf blade. As such, leaf venation is a pervasive example of a complex biological transport network. Transport networks optimized for efficiency have been shown to be loopless, a prediction at odds with the large number of loops present on dicotelydon leafs. Here, we consider robustness to damage and fluctuations in the load (transpiration rate across the leaf blade) as possible reasons for the formation of loops, and show that, in both cases, loops lead to a better performing network.