pressure-flow theory

Pressure-flow theory explains how plants transport sugars and water through their phloem. It states that sugars produced in the leaves create high pressure in the phloem (source), causing the fluid to move toward areas of lower pressure (sink), such as roots or growing tissues. This pressure difference drives the flow of sap, carrying nutrients where they are needed for growth and storage. The process relies on the generation of osmotic pressure from the sugars and the movement of water to maintain these pressure gradients, ensuring efficient distribution throughout the plant.