Figure 1. One-by-one stamen movement in Parnassia palustris.

The first stamen (□) elongates its filament slowly and its anther starts dehiscence after about one day later when the filament reached its maximum length (A). The filament deflexes about one day later and the stamen bends out of the floral center (filament angle ≧45°, indicated by the horizontal dash line); simultaneously the second stamen (▪) begins its filament elongation (B). Similarly, the third (○), fourth (•), and fifth (◊) stamens start their filament elongation only after the former stamen has moved out of the floral center (C, D, E). The number next to each stamen in (E) indicates the movement sequence (note that the dehisced anthers always abscise during the movement process). Shaded areas indicate night-time.