Roots: drinking, eating, breathing
What do roots do all day, down in the dark?
You can’t see them, and they hardly move. Yet a plant can’t live without them.
They look like plain strings. What are they up to?
You drink with a straw, eat with your mouth, and breathe with your nose.
Roots do all three jobs, all at the same time.
Look at a root up close. Just behind the tip, it is fuzzy with tiny threads.
These threads are called root hairsTiny threads near the end of a root that soak up water and plant food.
See it in the glossary.
- A · root hairs
- B · root tip
- C · main root
The root tip, at the very end, keeps growing longer. It pushes between soil bits into new spots.
The thick main root carries water up toward the stem.
Root hairs touch the water in the soil gaps. They soak it in, like lots of tiny straws.
More hairs means more water gets in.
Plant food is dissolved in that water. Roots pull the food in.
Pulling food in often takes energy, like carrying heavy bags home.
To get energy, roots breathe in air from the soil gaps.
If soil stays soaked, water fills every gap. Then roots can’t breathe, and the plant droops.
Your turn. Name the parts.
Match each name to a letter on the root.
Match each name to a letter.
Tap a letter, then tap its name.
Which name goes with A?
Match each name to a letter.
The answer:
- A · root hairs Tiny threads that soak up water and food.
- B · root tip The end that grows and pushes into new soil.
- C · main root The thick part that carries water up to the stem.
In a tub of water, there are no soil gaps full of air.
So growers bubble air into the water. The roots get their air from the bubbles.
- A · net pot & seedling
- B · roots
- C · air stone
Check 1 of 3
Where on a root do you find most root hairs?
Show the answer
A little way back from the tip. Right. They grow just behind the growing tip.
Check 2 of 3
Why do roots need air?
Show the answer
To get energy for their work. Right. Roots use air to get energy from sugar.
Check 3 of 3
A pot sits in a tray of water for weeks. The plant droops. Why?
Show the answer
Water filled every gap, so roots couldn't breathe. Right. Soaked soil has no room left for air.
You just learned how roots drink, eat, and breathe.
Next up: Plant food: the nutrients and what each one is for.
Go deeper: inside a rootOpenClose
Each root hair is one cell on the root’s outer layer that has grown long and thin.
Huge numbers of root hairs give a root far more surface to touch water. Most live only a day or two to a few weeks. Books differ on how long.
Roots take in oxygen and use it to break down sugar sent down from the leaves. This is called respiration.
Root cells spend that energy pulling in many nutrients, even when the soil water holds only a little of them. Without oxygen, this uptake slows down.
A root cap covers the very tip. It protects the growing cells as the tip pushes through soil.
Some wetland plants, such as rice, grow air-filled channels in their roots. Oxygen moves down through them from the shoot to the root tips.
Sources
- VanDerZanden, A. M. Vegetative Plant Parts. EM 9904. Oregon State University Extension Service, 2008 (reviewed 2024). Link
- Moore, K. A., and L. K. Bradley, eds. "3. Botany." North Carolina Extension Gardener Handbook, 2nd ed. NC State Extension, AG-831, 2022. Link
- Cogger, C. A Home Gardener's Guide to Soils and Fertilizers. EM063E. Washington State University Extension, 2014 (revised 2020). Link
- Jones, C., and K. Olson-Rutz. Plant Nutrition and Soil Fertility. Nutrient Management Module No. 2, 4449-2. Montana State University Extension, 2016. Link
- Pan, B. Nutrient Movement Towards and Into Plant Roots. Soils 441, Unit 1, Lesson 4. Washington State University. Link
- Wilted plants with lots of water. Southwest Yard & Garden. New Mexico State University, College of Agricultural, Consumer and Environmental Sciences, 2006. Link
- Trinklein, D. Wet Weather Woes. Integrated Pest Management, University of Missouri, 2015. Link
- Kaiser, C., and M. Ernst. Hydroponic Lettuce. CCD-CP-63. Center for Crop Diversification, University of Kentucky College of Agriculture, Food and Environment, 2016. Link
- Nelson, M., G. Langellotto, and L. Nackley. Hydro Hints: Deep Water Culture. EM 9455. Oregon State University Extension Service, 2025. Link
- Lin, C., T. Zhu, L. L. Peralta Ogorek, Y. Wang, M. Sauter, and O. Pedersen. The Pyramiding of Three Key Root Traits Aid Breeding of Flood-Tolerant Rice. Plants 11(15): 2033, 2022. Link