Turgidity-dependent petiole flexibility enables efficient water use by a tree subjected to water stress

• A multiphysics model of the role of wilting in the tree response to water stress is proposed.
• The model couples petiole mechanics, thermal energy balance, and xylem hydraulics.
• Turgidity-dependent petiole flexibility can significantly reduce the risk of cavitation.
• Petiole flexibility increases water use efficiency under water stress.

Water stress is a major cause of tree mortality. In response to drought, leaves wilt due to an increase in petiole flexibility. We present an analytical model coupling petiole mechanics, thermal balance, and xylem hydraulics to investigate the role of petiole flexibility in protecting a tree from water stress. Our model suggests that turgidity-dependent petiole flexibility can significantly attenuate the minimal xylem pressure and thus reduce the risk of cavitation. Moreover, we show that petiole flexibility increases water use efficiency by trees under water stress.