. Botany for agricultural students . Botany. 188 STEMS as to form distinct regions, such as pith, vascular cylinder, and cortex, which are more or less distinct regions in Dicotyledons. When cross sections of the Corn stem are studied with the microscope, such anatomical features as shown in Figure 166 may be seen. The cells of the rind are rectangular in shape, con- sist of a number of rows, and their walls are thickened and made woody for strength. The woody feature of the rind is character- istic of Grasses and Sedges, being much less prominent in other monocotyledonous stems, as, for examp
. Botany for agricultural students . Botany. 188 STEMS as to form distinct regions, such as pith, vascular cylinder, and cortex, which are more or less distinct regions in Dicotyledons. When cross sections of the Corn stem are studied with the microscope, such anatomical features as shown in Figure 166 may be seen. The cells of the rind are rectangular in shape, con- sist of a number of rows, and their walls are thickened and made woody for strength. The woody feature of the rind is character- istic of Grasses and Sedges, being much less prominent in other monocotyledonous stems, as, for example, in Lilies and Aspara- gus. The outer row of cells of the rind constitute the epider- mis, although in the Grasses the epidermal cells differ very little from other rind cells, except that they have silica and cutin de- posited in their outer walls. The vascular bundles, contain- ing numerous cells, show three or four large openings which are the large vessels of the xylem. Besides the large size of the pith cells as shown in the drawing, other features not shown, such as their storage function and their being so loosely joined as to form a spongy filling for the stem, should be mentioned. To study the complex structure of a vascular bundle, we must turn to a more highly magnified cross section of the bundle as shown in Figure 167. The vascular bundle consists of strength- ening and conductive tissues, the latter of which is composed of the xylem and -phloem, — the chief structures of all vascular bundles. In respect to the character of the vessels composing them, xylem and phloem show much uniformity throughout Flow- ering Plants. In the xylem the conductive tissues consist mainly of large ves~ sels, known as spiral, annular, or pitted vessels according to the character of the thickenings in their walls, as partly shown in Fig- ure 168 and more fully shown in Figure 169. The woody thicken- ings, which strengthen the cellulose walls of the vessels so that. Fig. lf)6. — A
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
