Do plants know which way is up and which way is down? Can they detect Earth’s gravity? Here is an experiment that will help you find out.
You will need:
radish seeds
clear glass jars
paper towels
box with a cover
Soak the radish seeds overnight in water. Line a clear jar with a damp paper towel and place the seeds between the towel and the jar, 1 inch from the lip. Keep the towel moist. Stand the jar in inside the box and close the lid to make it dark. When the seeds have germinated (a few days) and their stems extend an inch beyond the top of the jar, place the jar on its side as illustrated. Leave the jar in the dark again. Check the seedlings in a day. Have the stems and roots changed direction? Do you think that plants can feel gravity?
The effect of gravity on plants is called geotropism.
From Children’s Gardens: A Field Guide for Teachers, Parents and Volunteers by Elizabeth Bremner and John Pusey, Illustrations by Caroline Arnold