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    The pathway of radial water movement in tree stems presents an unknown with respect to whole-tree hydraulics. Radial profiles have shown substantial axial sap flow in deeper layers of sapwood (that may lack direct connection to transpiring leaves), which suggests the existence of a radial pathway for water movement. Rays in tree stems include ray tracheids and/or ray parenchyma cells and may offer such a pathway for radial water transport. This study investigated relationships between radial hydraulic conductivity and ray anatomical and stem morphological characteristics in the stems of three conifer species whose distributions span a natural aridity gradient across the Cascade Mountain range in Oregon, United States.

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    Barnard, David M.; Lachenbruch, Barbara; McCulloh, Katherine A.; Kitin, Peter; Meinzer, Frederick C. 2013. Do ray cells provide a pathway for radial water movement in the stems of conifer trees? American Journal of Botany. 100(2): 322-331.


    conifers, drought, hydraulic architecture, hydraulic conductivity, radial conductivity, ray parenchyma, ray tracheids, xylem anatomy

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