Fig. 4

Flight-attitude changes of fruit during falling in Firmiana simplex. a Experimental samples of actual fruit and paper models containing only one seed per fruit. b Posture changes of experimental samples during falling. The coloured bars represent different postures: green, downward acceleration; yellow, tumbling; orange, decelerated spinning; red, stable spinning; black, falling in a near straight line. The number 0 identifies the actual fruit and other sequential numbers identify different paper models: 1, Model I, in which the surface curvature of all areas were similar to the actual pericarp; 2, Model II, in which the curvature of the ovary area was similar to the actual pericarp but the top area was flat; 3, Model III, in which the curvature of the top was similar to the actual pericarp but the ovary area was flat; 4, Model IV, in which all areas were flat