Capillary action alone cannot account for the movement of water through the xylem because capillary action

Question

Quizplus · Accepted Answer

Capillary action is more effective in narrow tubes because the adhesion between the water molecules and the walls of the tube can pull the water column upward against gravity. The xylem vessels are relatively narrow, which theoretically would support capillary action, but the height to which water needs to be moved in tall trees cannot be achieved by capillary action alone, hence the need for additional mechanisms like transpiration pull. However, the statement that capillary action requires vessels that are much smaller in diameter than those found in the xylem is incorrect because xylem vessels are already quite narrow, making them suitable for capillary action to some extent.

Capillary Action Alone Cannot Account for the Movement of Water