Fig. 1

Cavitation in plants. a Light micrograph showing an air bubble formed by cavitation in the vein of a walnut leaf. b Vulnerability curves showing the increase in cavitation with decreasing xylem pressure during drought. Cavitation was initially thought to occur only in conditions of intense drought stress after stomatal closure (plain blue curve). Studies carried out in the last decade suggested that cavitation might be much more common than previously thought (dashed red curve). However, this view should now be overturned as major biases have been reported with the techniques used in recent years. Photo credits: Hervé Cochard (INRA, Clermont-Ferrand, France)