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

Water potential of turgor loss point ( ${\phi }_{\mathrm{TLP}}$ ) serves as an indicator of plant drought acclimation strategies and is closely linked to water loss. While leaf ${\phi }_{\mathrm{TLP}}$ has been extensively studied, little is known about flower ${\phi }_{\mathrm{TLP}}$ , flower drought acclimation strategies and the relationship between flower and leaf hydraulics. 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, 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 ${\phi }_{\mathrm{TLP}}$ under drought. (2) Unlike leaves, higher flower ${\phi }_{\mathrm{TLP}}$ does not effectively reduce water loss. (3) Drought avoidance in flowers is accomplished through easier decaying, and less dry mass is allocated to flowers to reduce carbon loss. (4) Morphological adaptations enable flowers to maintain attractiveness and reproductive function despite water stress.