No two roots are alike; that is, they vary among themselves as stems and leaves do. Each kind of plant has its own form or habit of root (Fig. [39]). Carefully wash away the soil from the roots of any two related plants, as oats and wheat, and note the differences in size, depth, direction, mode of branching, number of fibrils, colour, and other features. The character of the root system often governs the treatment that the farmer should give the soil in which the plant or crop grows.
Fig. 39.—Roots of Barley at A and Corn at B.
Carefully trace the differences.
Roots differ not only in their form and habit, but also in colour of tissue, character of bark or rind, and other features. It is excellent practice to try to identify different plants by means of their roots. Let each pupil bring to school two plants with the roots very carefully dug up, as cotton, corn, potato, bean, wheat, rye, timothy, pumpkin, clover, sweet pea, raspberry, strawberry, or other common plants.
Root Systems of Weeds.—Some weeds are pestiferous because they seed abundantly, and others because their underground parts run deep or far and are persistent. Make out the root systems in the six worst weeds in your locality.
CHAPTER VIII
THE ROOT.—FUNCTION AND STRUCTURE
The function of roots is twofold,—to provide support or anchorage for the plant, and to collect and convey food materials. The first function is considered in Chapter VII; we may now give attention in more detail to the second.
Fig. 40.—Wheat growing under Different Soil Treatments. Soil deficient in nitrogen; commercial nitrogen applied to pot 3 (on right).
The feeding surface of the roots is near their ends. As the roots become old and hard, they serve only as channels through which food passes and as hold-fasts or supports for the plant. The root hold of a plant is very strong. Slowly pull upwards on some plant, and note how firmly it is anchored in the soil.