Water relations and morphology of Cryptomeria japonica leaves vary with crown position

Seasonal changes of water relations and morphology were studied for Cryptomeria japonica leaves collected from top and bottom of mature tall trees. Both water potential at turgor loss and osmotic potential at full turgidity were lower in upper leaves than in lower leaves. Upper leaves had less amount of air space with greater amount of water per unit leaf volume compared to lower leaves. These results indicate that leaves of higher position adapt to water stress morphologically as well as maintaining positive turgor through osmotic adjustment.