Figure 2. Description of the model: transition from open (solid lines) to closed state (dashed lines). The system has cylindrical symmetry and the leaf (from 0 to L) is modeled as a circle. L – the length of the leaf; β – angle at the center of this circle; R – radius of curvature; α – initial angle at the midrib (does not change); ξ – an arbitrary point at the leaf; and γ - the angle at the center of curvature corresponding to this point ξ.