Plants and their children

by Frances Theodora Parsons

But the earth broth which the roots supply is not the only article of importance in the plant’s bill of fare.

The air about us holds one thing that every plant needs as food.

This air is a mixture of several things. Just as the tea we drink is a mixture of tea and water, and milk and sugar, so the air is a mixture of oxygen and nitrogen, and water and carbonic-acid gas.

Oxygen, nitrogen, and carbonic-acid gas,—each one of these three things that help to make the air is what we call a gas, and one of these gases is made of two things. Carbonic-acid gas is made of oxygen and carbon.

Now, carbon is the food which is needed by every plant. But the carbon in the air is held tightly in the grasp of the oxygen, with which it makes the gas called carbonic-acid gas.

To get possession of this carbon, the plant must contrive to break up the gas, and then to seize and keep by force the carbon.

This seems like a rather difficult performance, does it not? For when a gas is made of two different things, you can be pretty sure that these keep a firm hold on each other, and that it is not altogether easy to tear them apart.

Now, how does the plant meet this difficulty?

You cannot guess by yourselves how this is done, so I must tell you the whole story.

Certain cells in the plant are trained from birth for this special work,—the work of getting possession of the carbon needed for plant food. These little cells take in the carbonic-acid gas from the air; then they break it up, tearing the carbon from the close embrace of the oxygen, pushing the oxygen back into the air it came from, and turning the carbon over to the plant to be stored away till needed as food.