Lesson 1
A plant's tiny straws
Look closely at a young root and you'll see fuzz near the tip. That fuzz is made of root hairs, and each root hair is one long, skinny cell!
- Root hairs reach out between bits of soil to find water.
- Being long and thin gives them lots of outside surface to soak up water fast.
- They don't have chloroplasts. They live underground in the dark, so they can't use sunlight anyway!
Wow!
Scientists once counted the roots of a single rye plant. It had about 14 billion root hairs!
Lesson 2
How root hairs drink
Root hairs take in two things:
- Water, which every plant cell needs.
- Minerals, like nitrogen, which help the plant grow. They're like vitamins for plants.
The inside of a root hair cell is more crowded with sugars and salts than the water in the soil. Water naturally moves from where there's more water to where there's less, so it flows into the root hair. This is called osmosis (oz-MOH-sis).
From the root hair, water passes from cell to cell into the middle of the root, then into the plant's water pipes, the xylem.
Try this
Scroll up to the 3D root and press Drink water to see the water's path.
Lesson 3
Grow your own root hairs
Root hairs are tiny and easy to break. That's why gardeners move plants gently and keep some soil around the roots.
Try this: sprout some seeds
Fold a wet paper towel and put a few radish or bean seeds on it. Put it in a clear plastic bag and leave it somewhere warm. In a few days, the seeds will sprout roots. Look with a magnifying glass. See the white fuzz? Those are root hairs!
Wow!
Each root hair only lives for a few days to a few weeks. New ones keep growing as the root tip pushes deeper.