Fig. 1.

Digital representation of embolism recorded optically during leaf drying in the fern Adiantum. (A) Leaf illuminated by transmitted light. (Scale bar, 5 mm.) (B–E) The result of image analysis, showing the progression of embolism after (B) 2 h 5 min, (C) 4 h 10 min, (D), 6 h 15 min, and (E) 8 h 20 min. The darkening of pixels between successive images (30 s apart) by embolism is detected by image difference. If the darkening exceeds a threshold, these pixels are assigned as white (see Movies S1 and S2 for further explanation).