Low Vulnerability to Xylem Embolism in Leaves and Stems of North American Oaks.

Although recent findings suggest that xylem embolism represents a significant, drought-induced damaging process in land plants, substantial debate surrounds the capacity of long-vesseled, ring-porous species to resist embolism. We investigated whether recent methodological developments could help resolve this controversy within , a long-vesseled, ring-porous temperate angiosperm genus, and shed further light on the importance of xylem vulnerability to embolism as an indicator of drought tolerance. We used the optical technique to quantify leaf and stem xylem vulnerability to embolism of eight species from the Mediterranean-type climate region of California to examine absolute measures of resistance to embolism as well as any potential hydraulic segmentation between tissue types.