Fig 4. Kinematics of false indusia situated on cut-off pinnule margins.

(A) Motion of a false indusium recorded from lateral, frontal and top view in our microscopy lab (~23° Celsius, ~50%rh). The false indusium performs a curvature inversion, rotates around its connection line to the pinnule, and its lateral regions flap towards the middle part. (B) Motion of another false indusium in greater detail. (C-E) When the false indusium is in its fully open state (as seen here from different angles), the sporangia (here empty already) point into different directions, an arrangement for which we hypothesize that it promotes spore scattering. (F) The desiccation-driven opening motion is reversible because open false indusia completely re-close under water.