Virginia Sharum, age 11, of Sioux City Iowa, for her question:

Do plants sleep?

Of course a plant don’t not close its eyes, nod its head and fall asleep as we do. Nevertheless, it does rest. All green plants stop work whop the sun sets. Most plants lose their leaves and. stop all growing activities during the winter months. Even the evergreen plants of the tropics stop growing for e few months from time to time. So all plants have their busy times and their times of rest.

Whoa we fall asleep, certain body activities go on at a reduced rate. The lungs slow down but they continue to breaths. The heart slows down but the blood continuous to circulate. When a plant rests, certain of its activities also go on at a reduced rate.

A plant must breathe. It takes in oxygen and returns waste carbon dioxide to the air, just as we do. However, it has no nose. The air passes into and out of the plant through tiny pores in the leaves and stems. The plant needs oxygen day and night, just as we do. So, day and night, winter and summer, a plant takes in oxygen and sends out carbon dioxide into the air as it breathes.

During the day still another process goes on. All the green leaves and stems are busy making food. The recipe needs water, carbon dioxide and sunlight. The carbon is removed and plain, fresh oxygen returned to the air, which is oxygen over and above what the plants need to breathe. This explains why this work stops at sundown. There is no more sunlight for the magic recipe.

It also explains why we remove green plants from the sick room at night. In the dark the plant no longer pours out surplus oxygen. But its breathing goes on as usual and carbon dioxide is added to the air. And, while we sleep, our lungs need oxygen, not carbon dioxide, just as they do in the daytime.

So, we can say that even a lush green tree goon to sleep at night. Its idea of sleep, however, is much different from ours.

Some animals hibernate during the winter months. Food is scarce and the temperature is too cold for them. Many trees also hibernate during the winter, though they have their own ideas of hibernation. In the fall, as we know, the loaves turn color, dry up and fall off. Those trees have no greenery with which to make food. All that work stops. The trees look bare and deed. However, they are not dead, merely resting.

Moisture evaporates from the leaves and when the tree is bare the sap must slow down. The ground, too, is frozen and this cuts down the supply of sap. No growth takes place during this period of rust.

Evergreens keep their leaves summer and winter. A pine tree can make food on a clear frosty day. Nevertheless, it does no continua to grow all year round. Tropical trees have sunlight and moisture all year round. But, for some mason we do not understand, they too must take long rests during which that' add no new growth.