Question

Why do plants growing in dry regions have very deep root systems?

Answer 1

• Roots grow downward (positive geotropism) to reach moisture stored in deeper soil layers or the water table when the surface is dry.
• Deep roots branch widely and bear many root hairs, greatly increasing absorptive surface area so the plant can take up the limited water.
• Root hairs contain concentrated cell sap and have thin walls, allowing water to enter by osmosis; deep rooting also improves anchorage in loose, dry soils.