How a Tall Tree Drinks
A tall tree may have leaves that are far above the ground, yet it never has a drinking fountain. How does water get all the way to the top?
The journey starts underground. A tree's roots spread through the soil, and the tips of the roots are covered with tiny hairs. These root hairs soak up water and minerals from the soil, like thousands of little straws.
From the roots, the water enters narrow tubes that run up through the trunk and branches. Think of them as a long set of pipes, hidden just under the bark. The tubes carry water all the way to the leaves.
At the leaves, something interesting happens. The surface of a leaf has many tiny openings. Through these openings, a leaf lets out water as vapor, which is a very fine mist you cannot see. When water leaves the top of the tree this way, more water is pulled up the tubes to replace it. Scientists say it is a bit like drinking through a straw, since pulling at the top draws the liquid upward.
Leaves also use some of the water, along with sunlight, to make food for the tree.
On a warm day, a large tree can send a great amount of water into the air, which is one reason a forest feels cool and fresh.