The structure that transports food synthesized in the leaves to different parts of the plant is called the phloem. The phloem is a complex tissue made up of specialized cells that form a network of tubes throughout the plant, allowing for the transport of sugars, nutrients, and other organic molecules.

Structure of Phloem:
The phloem consists of four main types of cells:
1. Sieve tube elements: These are the main conducting cells of the phloem. They are long, cylindrical cells that are connected end to end to form sieve tubes. The end walls of these cells contain sieve plates, which have pores that allow for the movement of materials between adjacent cells.
2. Companion cells: Each sieve tube element is closely associated with a companion cell. Companion cells provide metabolic support to the sieve tube elements by supplying them with energy-rich molecules and helping to maintain their cellular functions.
3. Phloem fibers: These cells provide support to the phloem tissue. They are long, elongated cells with thick cell walls, providing strength and rigidity to the phloem.
4. Phloem parenchyma: These are thin-walled cells that surround the other phloem cells. They store food reserves and provide additional support to the phloem tissue.

Transport of Food:
The transport of food in the phloem occurs through a process called translocation. This process involves the movement of sugars, primarily sucrose, from sources to sinks within the plant.

Sources: Sources refer to the sites of sugar production, which are typically the leaves. In the leaves, photosynthesis occurs, producing sugars that are transported into the phloem. These sugars are then loaded into the sieve tube elements and transported to other parts of the plant.

Sinks: Sinks are the sites where sugars are utilized or stored. They can be growing regions such as roots, fruits, or developing leaves. The sugars are unloaded from the sieve tube elements and utilized by the sink tissues for growth, energy production, or storage.

Transport Mechanism:
The transport of sugars in the phloem occurs through a pressure flow mechanism. The loading of sugars into the sieve tube elements at the source creates a high concentration of sugars, resulting in osmotic pressure. This pressure forces the sugars to move from high concentration areas (sources) to low concentration areas (sinks) through the sieve tubes. The movement of sugars is facilitated by the pressure gradient and supported by the metabolic activity of companion cells.

In summary, the phloem is the plant tissue responsible for the transportation of food synthesized in the leaves to different parts of the plant. It consists of specialized cells, including sieve tube elements, companion cells, phloem fibers, and phloem parenchyma. The transport of sugars occurs through the process of translocation, which involves loading sugars at the source and unloading them at the sink. The pressure flow mechanism drives the movement of sugars through the phloem, allowing for efficient distribution of nutrients throughout the plant.