. Botany all the year round; a practical text-book for schools. Botany. 170 THE STEM PROPER. 317. â Section of branch showing knot. â circumference of the stem; how many years has the tree lived since the knot was formed ? Does this agree with the age of the knot as deduced from its own rings ? (As the tree may con- tinue to live and grow indefinitely after the bough which formed the knot died or was cut away, there will probably be no correspondence between the two sets of rings, especially in the case of old knots that have been covered up and embedded in the wood.) The longer a dead branch
. Botany all the year round; a practical text-book for schools. Botany. 170 THE STEM PROPER. 317. â Section of branch showing knot. â circumference of the stem; how many years has the tree lived since the knot was formed ? Does this agree with the age of the knot as deduced from its own rings ? (As the tree may con- tinue to live and grow indefinitely after the bough which formed the knot died or was cut away, there will probably be no correspondence between the two sets of rings, especially in the case of old knots that have been covered up and embedded in the wood.) The longer a dead branch remains on a tree the more rings of growth will form around it before covering it up, and the greater will be the disturbance caused by it. Hence, timber trees should be pruned while very young, and the parts removed should be cut as close as possible to the main branch or trunk. Some- times knots injure lumber very much by falling out and leaving the holes that are so often seen in pine boards. In other cases, however, when the knots are very small, the irregular markings caused by them add greatly to the beauty of the wood. The peculiar marking of bird's-eye maple is caused by abortive buds buried in the wood. 11 y.^\ 318 319 318, 319.â Diagrams of tree trunks, showing knots of dif- ferent ages: 318, from tree grown in the open; 319, from tree grown in a dense forest. PRACTICAL QUESTIONS 1. Name the principal timber trees of your neighborhood. What gives to each its special value? 2. Which is better for timber, a tree grown in the open, or one in a forest, and why? (239.) 3. What are the objects to be attained in pruning timber trees? Orchard and ornamental trees?. 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 original Andrews, Eliza Frances, b. 1840. New York, Cincinnati [etc. ] American book company
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