Fig 7. Beech seedling shapes just after tilting and at photogravitropic equilibrium in an anisotropic light environment, for different values of initial tilting.

Initial shape (blue symbols) and shape at photogravitropic equilibrium (red symbols) obtained by photo digitizing with Image J. Dates of photos are indicated on the graph (Julian days). A, B: Pots were tilted 5° and 15° from the vertical, respectively. No movement could be detected. C, D: Pots were tilted 25° from the vertical. Tree exhibited no movement (C), or movement (D). E, F: Pots were tilted 35° from the vertical. Trees exhibited a visible movement spread throughout the stem length.