. Bulletin (Pennsylvania Department of Forestry), no. 11. Forests and forestry. 34 branches strive for the leadership but they are such close competitors that neither can win out. The result is a *'stag-headed" tree. Again a dormant bud may be stimulated into activity with the result that no lateral branch obtains the leadership. After studying these growth forms, one is inclined to think that the terminal shoot pre- vents the erect growth of the lateral branches. Environment has a marked influence. The form of a tree growing on an exposed mountain top diff'ers very much from one growing
. Bulletin (Pennsylvania Department of Forestry), no. 11. Forests and forestry. 34 branches strive for the leadership but they are such close competitors that neither can win out. The result is a *'stag-headed" tree. Again a dormant bud may be stimulated into activity with the result that no lateral branch obtains the leadership. After studying these growth forms, one is inclined to think that the terminal shoot pre- vents the erect growth of the lateral branches. Environment has a marked influence. The form of a tree growing on an exposed mountain top diff'ers very much from one growing on sheltered bottomland. An open grown tree has a form entirely dif- ferent from one grown in dense forest stand. The form of open grown specimens varies with the species. Two different species of Pine shown in Fig. 34 grew side by side in the same environment and still developed entirely different crowns. Open grown trees usually branch near the ground and have a broad, deep, symmetrical crown, while trees grown in dense forest stand usually branch far- ther from the ground and have a long clean trunk with a shallow and often irregular and unsymmetrical crown. Trees grown in a dense stand may not be so attractive as those grown in the open but they yield a much higher grade of wood, since the lateral branches which produce many of the knots in lumber are removed early in the life histOr}^ of the tree. The density of the forest stand should be so regulated that on every acre of soil not only the greatest quantity but also the best quality of wood is produced. Two kinds of branching are usually recognized, the excurrent or upright and the deliquescent or spreading. When the main trunk is continuous and extends upward to the tip without dividing it is known as excurrent, and when the main trunk is not continuous but divides and subdivides into more or less equal parts it is known as deliquescent. Most of our evergreen species have the excurrent type of branching, while most of ou
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