A comprehensive understanding of the systems behind vertical transport of water in tall trees is crucial when predicting the susceptibility of these long-lived organisms to drought.
Pfautsch et al. use detailed physiological and wood anatomical analyses of 20m tall Eucalyptus grandis (Myrtaceae) trees to unveil that – contrary to widespread assumptions – the widest xylem vessels were guarded by the thickest pit membranes, located several meters above the ground. The results explain how ultrastructural traits of xylem help improve the efficiency and apical dominance of water transport and stress the importance of studying hydraulic architecture at the whole-tree scale.
