. Cyclopedia of farm crops, a popular survey of crops and crop-making methods in the United States and Canada;. Farm produce; Agriculture. Fig. 38. Bud Of brusaels sprouts cut lengthwise. f, fibrous bundles; &^ the crumpled leaf- Fig. 39. Diagram showing the gir- der-like arrangement of strengthening tissues ) in a bulrush. Scirpus. point (axil) where the leaf is joined to the stem. Not all branches develop. Many that start cannot get sufficient light and soon die. This is known as " self-pruning," and is seen especially in forest trees, which produce lumber free fro
. Cyclopedia of farm crops, a popular survey of crops and crop-making methods in the United States and Canada;. Farm produce; Agriculture. Fig. 38. Bud Of brusaels sprouts cut lengthwise. f, fibrous bundles; &^ the crumpled leaf- Fig. 39. Diagram showing the gir- der-like arrangement of strengthening tissues ) in a bulrush. Scirpus. point (axil) where the leaf is joined to the stem. Not all branches develop. Many that start cannot get sufficient light and soon die. This is known as " self-pruning," and is seen especially in forest trees, which produce lumber free from knots. Many buds do not even start to de- velop but remain dormant, often for many years, growing just enough to keep pace with the annual thickening of the tree. They may be traced back to the center of the tree, sometimes several feet long, but no thicker than a lead-pencil. New or adven- titious buds may be formed; such buds, becoming crowded and distorting the grain of the wood, cause the appearance familiar in bird's-eye maple. The stem requires strengthening tissue in order to sustain the weight of its branches and the force of the wind. In the tree the accumulated wood serves every purpose, but in the herbaceous stem special strengthening tissue is formed, quite dis- tinct from the wood. In parts of the stem that are lengthening, this tissue consists of collenchyma cells, whose walls, thickened at the corners only, have thin places by means of which food and water may be absorbed (Fig. 24). Their growth keeps paca with that of the stem, otherwise they would soon break and become useless. In older parts of the stem that have ceased lengthening, the mechanical cells, sclerenchyma, have walls equally thickened all around, except at the pits ; when the thickening reaches a certain point the cells die, but their use- fulness is not impaired thereby. The distribution of mechanical tissue in the stem presents a wonderful example of useful arrange- ment to secure the highest d
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectagriculture, bookyear
