Phloem Sap Movement

Phloem transports food materials (mainly sucrose) in plants through a process called translocation:

• Loading: Sucrose is actively loaded into sieve tubes at the source (e.g., leaves)
• Bulk flow: A pressure gradient is created, causing sap to flow from high to low pressure areas
• Unloading: Sucrose is unloaded at the sink (e.g., roots, fruits) through active or passive processes

This movement is bidirectional and follows the pressure flow hypothesis proposed by Ernst Münch.