Relationship between hydraulic resistance and leaf morphology in broadleafQuercus species: a new interpretation of leaf lobation

We investigated the relationship between leaf shape and leaf hydraulic resi stance in a set of broadleaf Quercus tree species (Q. cerris, Q. frainetto, Q. petraea, Q. pyrenaica, Q. robur, Q. rubra, Q. velutina). Seedlings of a ll the studied species were grown under uniform environmental conditions. A new high-pressure flowmeter was designed to measure leaf-blade hydraulic r esistance. Leaf shape was characterised by the complexity of leaf outline w hich was regarded as an estimate of leaf lobation. This was done using the box-counting fractal dimension of the leaf silhouette. Leaf hydraulic resis tance was negatively related to leaf lobation. It is suggested that the low er hydraulic resistance in deeply lobed leaves may constitute a mechanism f or improving water balance under dry atmospheric conditions.