Skip to story
ELI5 Yahaaa

Anchor and straw

What Do Roots Do?

Roots hold a plant down, drink water and minerals, and trade with fungi underground.

Anchor the plantagainst windAbsorb water anddissolved mineralsTrade sugar with soilfungi
Three jobs, all underground.

  1. Step 1 of 5

    They hold the plant down.

    A tree in windWind pushes itoverRoots grip andhold

    A tree catches enormous wind force. Its roots spread wide and grip soil so the whole thing does not simply blow over.

  2. Step 2 of 5

    Root hairs do the drinking.

    A root tip Millions of microscopichairs — the absorbingsurface

    Just behind each root tip are millions of microscopic hairs. They are almost all of the absorbing surface, and they are what tears when you transplant carelessly.

  3. Step 3 of 5

    Water is pulled up, not pushed.

    1 Waterevaporates fromleaves2 That pulls thecolumn upward3 More water isdrawn in at theroots

    Evaporation from leaves creates a pull that drags the whole water column upward. There is no pump — the leaves do the sucking.

  4. Step 4 of 5

    Minerals come dissolved in that water.

    What roots take Water and dissolvedmineralsWhat they do not take Solid soil — plants donot eat it

    Nitrogen, phosphorus and potassium ride up with the water. Soil is not food — it is a mineral supply plus something to grip.

  5. Step 5 of 5

    Most plants trade with fungi.

    Plant gives sugar Fungus givesmineralsA trade, both directions

    Fungal threads extend the root network enormously and hand over minerals in exchange for sugar. Most plants rely on this to thrive.

    A single rye plant was measured with over 600 km of root and root hair, in a few litres of soil.

The short version

Roots anchor the plant, absorb water and minerals through microscopic hairs, and trade with soil fungi.

Try it yourself

Grow a bean on damp cotton wool in a jar. The root hairs are visible as fuzz just behind the tip.

Topics

Next tiny story