Root hair cells

Root hair cells are found on the outer surface of a root. They take up water and mineral ions from the soil.

Each root hair cell has a long, thin extension that reaches into the soil. This extension makes the cell recognisable in diagrams and images: it looks like a narrow hair projecting from the root surface.

The extensions give the root a large surface area in contact with the soil. This provides more area through which water and mineral ions can enter the root, increasing their uptake.

Pathway of water through a plant

Water enters the plant from the soil through root hair cells on the surface of the root. It then passes through the cells of the root cortex and enters the xylem.

The xylem carries water through the root and stem into the leaf. In the leaf, water leaves the xylem and reaches the mesophyll cells inside the leaf. Together, these structures provide a continuous route for water from the root to the leaf.

Tracing water transport with a stain

Water moving through a plant is normally difficult to see. Adding a suitable stain to the water makes its route through the above-ground parts visible.

As the plant takes up the stained water, colour appears in the xylem of the stem. Xylem is the tissue that carries water through the plant. The colour can also be seen along the route into the leaf.

Examining where the stain appears provides evidence of the pathway taken by the water: coloured regions show where the stained water has travelled.