Data analysis
Vulnerability curves were plotted and fitted using SigmaPlot 14 (Systat Software Inc., Erkrath, Germany). After testing data for normal distribution and homogeneity of variance, a one-way ANOVA was applied to test for significant difference between xylem embolism resistance of a detached leaf, and a leaf attached to a short or long branch. An independent t-test was applied to determine whether the optical and pneumatic method differed. Statistics were performed in SPSS 22 (IBM, Armonk, New York, USA), and all graphs were drawn in SigmaPlot.