FIG. 7. Simulation of maize (Zea mays L.) root system architecture interacting with the environment. A plow pan layer impedes root growth at 35 cm depth. (A) General morphology of the simulated maize plant. (B) Simulated (+) and observed (·) root profiles, obtained by counting the number of colonized cells (2 x 2 cm) on vertical grids. The horizontal bar represents one standard deviation (from Pagès, 1999). (C) A simple example of simulated root growth around mechanical obstacles (rocks) in a homogeneous soil (from Prusinkiewicz, 1998).