Lesson guide · Lesson 6 · Grades 3–8 · 6 min

Water as a delivery system

How water carries nutrients in at the roots, up the stem, and out to every leaf, and what keeps it moving.

Open the lessonPrintable worksheet

Students will

  • Describe the path water takes from the roots to the leaves.
  • Explain that water carries nutrients through the plant.
  • Explain that water leaving the leaves pulls more water up the stem.

New words

xylem
Tiny tubes in a plant's stem that carry water up from the roots.
transpiration
Water leaving a plant's leaves as a gas you can't see.

Talk about it

What else works like a delivery system in your town? What happens when it stops?

Check questions and answers

  1. What does water carry from the roots up to the leaves?

    • Nutrients (answer) Right. Water is the delivery truck for plant food.
    • Sugar Not quite. Leaves make sugar themselves. Water brings nutrients up.
    • Soil Not quite. Roots take in water, not soil.

  2. What are the tiny tubes inside a stem called?

    • Xylem (answer) Right. Xylem tubes carry water up, a bit like straws.
    • Roots Not quite. Roots are at the bottom. The tubes run up the stem.
    • Leaves Not quite. Leaves are at the top. Look inside the stem.

  3. Water drifts out of the leaves. What does that do?

    • It pulls more water up the stem (answer) Right. Like sipping a straw, it tugs the water below upward.
    • It makes the roots grow longer Not quite. Think about the straw. What happens to the water below?
    • It stops the plant from drinking Not quite. It does the opposite. It keeps water moving up.

Sources

  • Moore, K. A., and L. K. Bradley, eds. "3. Botany." North Carolina Extension Gardener Handbook, 2nd ed. NC State Extension, AG-831, 2022.
  • Clark, M. A., M. Douglas, and J. Choi. "30.3 Roots." Biology 2e. OpenStax, 2018.
  • Clark, M. A., M. Douglas, and J. Choi. "30.5 Transport of Water and Solutes in Plants." Biology 2e. OpenStax, 2018.
  • Let's Experiment with Plant Plumbing. Washington State University and Master Gardener Foundation of King County.
  • U.S. Geological Survey. Celery draws up water from the roots into the top of the stalks. USGS Water Science School image, credit K. Doyle.
  • Transpiration - Water Movement through Plants: Introduction. Plant and Soil Sciences eLibrary (PASSel).
  • Transpiration - Water Movement through Plants: Major Plant Highlights. Plant and Soil Sciences eLibrary (PASSel).
  • U.S. Geological Survey. Evapotranspiration and the Water Cycle. USGS Water Science School, 2018.
  • Starbuck, C. J. Guttation: A Pressure Relief for Plants. Missouri Environment & Garden, Integrated Pest Management, University of Missouri, 2009.
  • Klepper, B., and M. R. Kaufmann. Removal of Salt from Xylem Sap by Leaves and Stems of Guttating Plants. Plant Physiology 41(10): 1743-1747, 1966.