The study of seasonal xylem hydraulics has predominantly focused on embolism-induced losses, whereas growth-driven increases in hydraulic capacity have received little attention. We assessed the intra-annual dynamics of xylem formation and gain of conductivity in the current-year ring of three species with contrasting tree-ring structure, sessile oak (Quercus petraea, ring-porous), European beech (Fagus sylvatica, diffuse-porous) and Norway spruce (Picea abies, conifer), using micro-cores collec