THE WONDERFUL MAIZE PLANT.
A sprouting grain of corn sends a pointed leaf, rolled into a close tube, up to the light, while a tapering root goes downward, and branches into fibrous feeding roots along its sides. Out of the tip of the leaf tube a slenderer tube rises, and carries the plant higher, while the first leaf spreads out flat. As the leaf arches its blade, the second one loosens, and the third appears. Each leaf holds its younger brother in a close protecting em brace until it is able to endure the hot sun, when this one becomes in turn the nurse of another. The stalk is hidden by the sheaths of the several leaves, until at last the tassel appears, and leaf making is at an end. In the angle of certain leaves the stem sends out short branches. These are clothed with crowded leaves, and topped with a bunch of long silks. Tassels and the miniature ears are the flower clusters of the corn plant.
The leaf of the corn plant. — All the food the roots gather is carried to the leaves for chem ical transformation into nutritious sap. Crude materials gathered from the soil and absorbed from the air, assemble in the leaf laboratories, where the energy of sunlight is used to convert raw materials into rich, starchy food, which flows back to supply the growing parts of the plant.
The arch of a corn leaf is graceful, indeed. What is far more important to the plant is the fact that the greatest possible amount of leaf surface is exposed to the direct rays of the sun. When the air is moist, "you can see corn grow" in mid summer. The starch factories are working at great pressure. Farmers say "you can hear it grow" by night. A multitude of snapping noises are heard, suggesting the lengthening of fibres. Quantities of water are exhaled as invisible vapor from pores located chiefly on the upper surface of each leaf. When the dry winds rob the soil of moisture, the roots go deeper. The leaves roll their edges inward and sometimes overlap, in order to reduce the amount of surface exposed to sun and wind. The pores are thus closed to save the water supply. When rains come, the normal con ditions are restored, and food-making becomes the chief business of the plant. Notice how the corn husks, even, spread out into leaves, to do their share of this work while their bases protect the ear.
Even the stalk is green, and able to join in the labors of the leaves.
How is it that the corn plant can carry so much sail, and yet not have its leaves whipped into strings by the winds? Test for yourselves the flexibility and strength of the midrib of a leaf, the fibres in the leaf margins, and in the tubular leaf base that sheathes the stalk. Notice the frilling of the leaf blade, especially near its joining with the sheath. Swing the whole leaf as far as possible, to find out what amount of play the leaf sheath allows by its own flexibility. What part of a circle is this play? Now hold the sheath tightly against the stalk, and find out the use of the frilling of the leaf blade. Pull the tip to left or right until the frill is straight. Reverse the direction, until the opposite frill is taken up.
How much play has the blade independent of the swinging sheath? What amount of play has the whole leaf? The leaf has a spiral twist in its midrib that enables it to avoid the full force of the wind. The frills enable the midrib to turn to left or right, almost as easily as if it were hinged. By swinging round the stalk, and getting out of the way as much as possible, the leaves avoid the slitting they would get if they were flat and rigidly inserted on the stalk. Much protection is afforded by stalks standing in close ranks in the field.
The rain-guard is one of the neatest devices a corn plant can show. It prevents water from getting down between leaf-sheath and stalk. Dirt accumulating there would cause the base of the leaf to rot off. Dirt would injure the ear by getting down between the tender green husks. The guards prevent this. Rain flows down the leaf trough. The stream parts at the guard, runs down the swollen joint of the stalk, and trickles down the outside of the sheath. From one leaf to another it leaps, and waters the roots. Loosen a number of leaves, and study the rain-guard. Study them on the outer husks. Pour or spray an imitation shower on the top of a corn plant, and see the course of the streams as they descend to the roots. See the accumulation of rubbish behind each rain-guard. Note the close fit of this process to the swollen joint of the stem.