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Why Trees Grow Erect

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The most casual observer must have been struck by the constancy with which the trunks of trees aim toward the zenith, never minding the slope on which they may he growing. In tapering trees like the Lombardy poplar, this is most noticeable, and in all trees whose trunks continue to the top, as do the firs, spruces and tamaracks. Less notice ably, but not less constantly, does this rule hold among the broad-crowned, diffuse trees, like the oaks and the maples. Only accident or the urgent necessity for light will cause a tree to lean in growing.

Among the most interesting phenomena of tree growth are the mani fest efforts made by crippled trees to get back to the evert position. Every branch seems to have inherent in it loyalty to old traditions, estab lished perhaps when the progenitors of all tree families, growing on the margins of old Paleozoic seas, stood up, manwise, and formally assumed dominion over the forms of plant life that groveled at their feet or looked up at them from lower levels. A tree thrown down may die of its wounds, but if it dues not die it seeks to assume an erect position. As long as there is life there is aspiration ! One of these courageous trees which I know is a young one that was crippled by the fall of a neighbor. It was partially uprooted. and its top was pinned to the earth, and smothered under the shaggy crown of the larger tree. When the few roots still in the ground recovered from the shock, they took fresh hold upon the soil, and a vigorous young shoot grew out of the prostrate stein. The tree's resources seem to have been withdrawn from the doomed top and thrown into this erect branch that forms a right angle with the old trunk. It is a most remarkable sight, this prone trunk with its roots in the air and its head in the dust, and out of its trunk growing this little tree as pretty and ,symmetrical and vigorous to all appearances as was the original tree before dire calamity overtook it. There is something almost sublime in the patience and the courage of plants! On a steep bank which has suffered, many a land-slide grows a poplar. Once it had a station far up, but its foundations were shaken while yet its roots were shallow, and it fell headlong down the slope. Catching upon a snag, the tree stopped half-way down the wall of the gorge, and a 51 mass of earth acenmulated I1p011 its upturned roots. The tree was thus

re-planted, head downward. Three years it has lieen growing. Its large branches still point down the bank, hilt the younger ones have turned and gone the other way. Through the framework of larger branches they have forced their way to liberty and light.

Set a basswood or a willow hranch in the ground upside down, and the tree which grows from it will be perfectly normal. The buds along the sides will open and the shouts bend upward as they lengthen. The terminal bud of a young larch has been killed. A lateral branch has bent up and become the leader. Gradually the kink is disappearing. and the stem will soon be as straight as ever. The picture shows a lower branch on a cottonwood tree. It is :1 record of struggles, disappoint ments and filial triumph. Can you read it? Some interesting observations have been recorded on the actions of crippled trees. A storm that some years ago swept the grounds of the Iowa Agricultural Experiment Station, partially uprooted several trees. A balsam fir which was bent over by the storm was later observed by Professor llessey to be gradually bringing its tip to the vertical position. The tender new growth was first noticed to he curving up. lly slow degrees the curve moved downward to WOOd that was two or three veers old when the storm took place. The report of these observations set other scientists to experimenting. Thomas Meehan, a prominent nurseryman and horticulturist of Philadelphia, took up a straight-stemmed. well grown arbor vital, and reset it with the stem at an of 45° with the horizon. Soon the tip began to bend toward the vertical. In three weeks the curve had extended down to the five-year-old wood, involving three feet of the top of the tree. The tip which first became erect.was thrown past the vertical by the bending below it. Gradually this tendency was corrected. and the tip Wa-S brought hack into line. At the end of the season the top of the tree, seven years' growth. stood upright! An interesting phase of the erecting habit is seen in weeping trees. The young twigs are flexible and dun p helplessly at first, but they stiffen and lift thenisehres when they grow older. Thus the youngest growth is constantly lifted higher and held farther out from the trunk. and the crown of the tree enlarged.

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