Drought Avoidance: A Shared Strategy for Perennial Herbaceous Flowers and Leaves through Distinct Mechanisms

Turgor loss point (φTLP) serves as an indicator of plant drought acclimation strategies and is closely linked to water loss. While leaf φTLP has been extensively studied, little is known about flower φTLP, particularly its role in the drought acclimation strategies of flowers or its integration into whole-plant responses. In a semi-arid to semi-humid grassland on the Inner Mongolia Plateau, precipitation was reduced by 0%, 20%, 50%, and 80% using shelters. Hydraulic traits, gas exchange, temperature and morphological traits of a native perennial herb, Bupleurum smithii, were measured in both flowers and leaves. Results revealed that: (1) Both flowers and leaves employ drought avoidance strategies, with increased φTLP under drought. (2) Unlike leaves, higher flower φTLP does not effectively reduce water loss. (3) Drought avoidance in flowers is accomplished through easier decaying, and less dry mass is allocated into flowers to reduce carbon loss. (4) Morphological adaptations enable flowers to maintain attractiveness and reproductive function despite water stress. This highlights the functional specialization of plant organs, with flowers prioritizing reproduction under resource constraints.