Internal Structure of Root:

The conducting tissues (xylem and phloem) of the root are grouped in the center to form a rod-shaped core, which extends throughout the length of the root.

Pericycle:

Outside the conducting tissues, there is a narrow layer of thin-walled cells, the pericycle. A single layer of cells, the endodermis, surrounds the pericycle layer. The remaining tissues of the root consist of a broad zone of large, thin-walled cells making up the cortex.

Cortex:

The cortex is bounded on the outside by a single layer of epidermal cells. Roots also have clusters of tiny root hairs, which are the extensions of epidermal cells.

Root hairs:

Root hairs provide a large surface area for absorption. They grow out into the spaces between soil particles where they are in direct contact with the water. The cytoplasm of the root hairs has a higher concentration of salts than the soil water, so water moves by osmosis into the root hairs. Salts also enter root hairs by diffusion or active transport. After they enter the root hairs, water and salts must move through the epidermis and cortex of the root, and then into the xylem tissue in the center of the root.