Stomatal patchiness and cellular computing.

Control of carbon dioxide and water vapor exchange between a leaf's interior and the surrounding air is accomplished by variations in the turgor pressures in the small epidermal and guard cells that cover the leaf's surface. These pressures respond to changes in light intensity and wavelength, temperature, CO2 concentration, and air humidity. The dynamical equations that describe such processes are formally identical to those that define computation in a two-layer, adaptive, cellular nonlinear network. This exact identification suggests that leaf gas-exchange processes can be understood as analog computation and that exploiting the output of two-layer, adaptive, cellular nonlinear networks might provide new tools in applied plant research.