Analysis of Pattern Formation on the Surface of Respiring Leaves

The process of photosynthesis is facilitated in a plant by pores in its surface called stomata. When a particular stoma is open, CO2 is absorbed through its aperture, but H2O is also lost due to evaporation. Thus a plant will seek a stomatal aperture that balances its need for CO2 with its aversion to H2O loss. In order to visualize a particular leaf’s stomatal aperture distribution and how it changes with time, fluorescence data is collected at regular intervals as digital images, resulting in a video sequence. In observing such data, plant biologist have noticed in over 200 plant species that, even under spatially varying environmental conditions, stomatal apertures are often synchronized into spatially extended patches. This behavior is observed even though patchiness often results in less than optimal local CO2 uptake for fixed water loss. It is not understood why stomatal patchiness occurs, and it is the objective of this paper to shed light on this phenomenon via the analysis of one such fluorescence video. In order to perform our analysis, we first extract the patches from the video via a 3D, PDE-based segmentation method. With the segmented video in hand we then analyze the patches and their dynamics using a variety of measures.