XVI International Botanical Congess

The pathway for water movement through plants is heterogeneous in terms of its surface wettability. Both the affinity of water for solid surfaces (summarized by the contact angle) and the permeability of these walls influences basic aspects of water uptake and transport. While water repellent surfaces are well known to occur in both roots and leaves, xylem conduits have been assumed to be completely wettable. Our measurements indicate that the contact angle of vessel walls are significantly greater than zero. We propose that these surface characteristics have important functional implications for the stability of water transport and the potential for the refilling of embolized vessels.