. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. Make a longitudinal section passing through the central portion of the root and extending an inch or two into the lower part of the stem. Do you find any sharp line of divi- sion between them? Notice the hard, woody axis that runs through the center. This is the vascular cylinder and con- tains the conducting vessels, the cut ends of which were shown in cross section in Fig. 76. 65. Distinctions between root and stem. — Pull off a branch from the stem and one from the root
. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. Make a longitudinal section passing through the central portion of the root and extending an inch or two into the lower part of the stem. Do you find any sharp line of divi- sion between them? Notice the hard, woody axis that runs through the center. This is the vascular cylinder and con- tains the conducting vessels, the cut ends of which were shown in cross section in Fig. 76. 65. Distinctions between root and stem. — Pull off a branch from the stem and one from the root; which comes off the more easily ? Examine the points of attachment of the two and see why this is so. This mode of branching from the central axis instead of from the external layers, as in the stem, is one marked distinction be- tween the structure of the two organs. In fig. 77.—Verti- stems, moreover, branches occur normally section of branching ab0ve the points of leaf insertion at the root, showing the branches, n, n, origi- nodes (46), while in the root they tend to a^/.^and'paS arrange themselves in straight vertical rows, through the cortex, The shoots and cions that often originate from them are not normal root branches, but outgrowths from irregular or adventitious buds, that may occur on any part of a plant. The root is not divided into nodes like the stem, and never bears leaves. 66. The active part of the root. — It is only the newest and most delicate parts of the root that pro- duce hairs and are engaged in the active work of absorp- tion, the older parts acting mainly as carriers. Hence, old roots lose much of their characteristic structure and , i j (, Fig. 78. — Root of a tree on the side of take on more and more of a guiiey, acting as Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the origina
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