To furcate or not to furcate: The dance between vessel number and diameter in leaves

Abstract

Documenting the ways that diameters of watertransporting conduits are deployed throughout plants is crucial for understanding hydraulic function and adaptation. Most studies have focused on stems, with many major controversies remaining regarding leaf conduits. Lechthaler et al. (2019) contribute to filling this crucial gap. Examining sycamore maple leaves, they show that conduits widen predictably and quickly with path length (even within vein orders); that conduits are very numerous near the terminal leaf veins but constant in number along the midrib and petiole; that total conductive area scales isometrically (slope of 1) with leaf area supplied; and that wider conduits are more vulnerable to cavitation. Their results confirm the need to revisit current theoretical hydraulic models and methodologies, and contribute significantly to clarifying the role of leaves in the new emerging framework in plant hydraulics.