. Botany for agricultural students. Plants. EXPOSURE TO LIGHT 241. Figure 222. Many trees as well as many herbaceous i)lants, such as Cotton, Clover, Alfalfa, Tomatoes, Potatoes, Buckwheat, and Flax, have the alternate arrangement of leaves. In the opposite arrangement two leaves appear at each node on opposite sides of the stem, and neighboring pairs are set more or less at right angles to each other, so that as one looks down from above each pair of leaves alternates in position with the pair above and with the pair below it as shown in Figure 223. The opposite arrangement is also common amo
. Botany for agricultural students. Plants. EXPOSURE TO LIGHT 241. Figure 222. Many trees as well as many herbaceous i)lants, such as Cotton, Clover, Alfalfa, Tomatoes, Potatoes, Buckwheat, and Flax, have the alternate arrangement of leaves. In the opposite arrangement two leaves appear at each node on opposite sides of the stem, and neighboring pairs are set more or less at right angles to each other, so that as one looks down from above each pair of leaves alternates in position with the pair above and with the pair below it as shown in Figure 223. The opposite arrangement is also common among both woody and herbaceous plants. In the whorled arrangement more than two leaves t- r>or t-w j i- • i ° I'iG. 225. — Dandelion viewed occur at a node, as illustrated in from above. The leaves form a Figure In this arrangement rosette and the lower leaves are the leaves are also so placed as to ^^^^ logger than the upper ones. shade each other as little as possible. In plants, like the Dandelion and Plantain, which have very short stems bearing many leaves, the leaves form a mat, called a rosette, on the surface of the ground. It is readily seen that leaves so closely crowded as they are in the rosette must shade each other considerably, but they have the advantage of being exposed less than those on elongated stems to the loss of water by transpiration. In the rosette much shading is eliminated b}^ a difference in length of petioles, for the outer and under leaves of the rosette have longer petioles which push their blades beyond those of the upper leaves, and in this way they escape the shade of the leaves above. This feature is noticeable in the rosette of the Dandelion shown in Figure 225. Another arrangement of leaves which is favorable to light exposure is called a leaf mosaic, being so named. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these ill
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectplants, bookyear1919
