Food is synthesised in the green parts of the leaf and is transported to all parts of the plant. For this plant has specialised organs called Phloem tissue. It has two components companion cells and sieve tubes. Companion cells load food products (Sucrose) from the green cells through the process called phloem loading. This process requires energy which they get from ATP’s.
After loading osmotic pressure of the sieve tube increases, as a result, water moves into the tube.
Cells which need food product has lower osmotic pressure in nearby sieve tubes. Food along with water moves to these cells passively, and the food is delivered to the cell. The process is called unloading. This process is also ATP dependent.
Unused or excess food is stored in roots and fruits.
