Compare a green plant with one that is ripe and yellowing. Is the guard still doing duty? What effect have the surface hairs on the water? Does it collect in drops, as on an oily surface, or does it spread ? The stalk.—The swollen rings are the nodes of the stalk. The lengths between are the internodes.
The word joint is used for both, so is ambiguous. The strength of the stalk is in the short, strong internodes near the bottom. The slenderer, longer ones are toward the top, where flexibility is re quired rather than strength. Below each node the fibres are most rigid, but they are found more tender toward the bottom of the internode. In this tender substance growth takes place; and all the internodes of the stalk are able to grow at the same time. This explains the remarkable speed of the plant's growth, when the roots are established in rich mellow soil. Each "joint" adds to its own length.
Corn goes down, sometimes, before a severe wind that loosens its roothold. The chief work of erecting the prostrate stalk is done by the stout lower internodes, which have power to bend, and thus lift the stalk. Have you seen corn, "lodged"
by wind, rise again in a short time_? The corn plant's feeding roots are fibrous and shallow in rich soil. In pulling up a plant we tear them loose, and leave in the earth the delicate root-hairs. Above ground a set of special roots spring from one or more nodes of the stalk. These are brace roots, stiff and tough, provided to hold the stalk in the ground, and to brace it. They act as anchors as well as props, resisting the pull and push of the wind. How many sets of brace roots can you find on a single plant? The farmer tries to hill the soil around the corn plants with his cultivator when he gives the last plowing. He knows that neither system of roots can do its work without a good grip on the soil. The deeper the roots are, the firmer the plant stands, and the better its chances to get food and water in abundance.