Here's why:

* Downward Growth: Gravity plays a big role, causing roots to grow downwards, searching for water and nutrients deeper in the soil. This is called geotropism.

* Lateral Growth: Roots also grow horizontally, spreading out to anchor the plant and access a wider area for resources.

* Toward Moisture: Roots are highly sensitive to moisture and will grow towards areas where water is available, even if it's not directly downwards. This is called hydrotropism.

* Towards Nutrients: Roots can also grow towards specific nutrients in the soil, such as nitrogen or phosphorus. This is called chemotropism.

Overall, the direction of root growth is determined by a combination of factors, including gravity, moisture availability, nutrient concentration, and the plant's needs.