. The anatomy of woody plants. Botany -- Anatomy. 2OO THE ANATOMY OF WOODY PLANTS rewluta. Toward the lower side of the figure is seen the phloem, composed of elements which in the main are arranged in regular radial rows indicating an origin from cambial activity. The upper region of the bundle is composed of xylem, consisting of very large elements which become progressively smaller and fewer in number in the downward direction. The lower point of this aggregation of cells is the protoxylem. This region is surrounded inferiorly by a few rows of parenchyma which give place in turn to more. FI
. The anatomy of woody plants. Botany -- Anatomy. 2OO THE ANATOMY OF WOODY PLANTS rewluta. Toward the lower side of the figure is seen the phloem, composed of elements which in the main are arranged in regular radial rows indicating an origin from cambial activity. The upper region of the bundle is composed of xylem, consisting of very large elements which become progressively smaller and fewer in number in the downward direction. The lower point of this aggregation of cells is the protoxylem. This region is surrounded inferiorly by a few rows of parenchyma which give place in turn to more. FIG. 147.—Transverse section of leaf of Cycas revoluta. Explanation in the text thick-walled elements of the xylem, in contact with the regular radial files of the cambium. The lower region of the xylem is the so-called centrifugal xylem; the upper portion broadening from the narrow protoxylem is the centripetal or cryptogamic xylem. The first-mentioned group of elements of the xylem are pitted in their character, as will be made clear in a subsequent longitudinal illus- tration. The latter, the so-called cryptogamic wood, is of impor- tance from the evolutionary standpoint because it indicates at once a clear relationship on the part of the Cycadales to the vascular cryptogams and to the lower and extinct gymnosperms. In the next figure (Fig. 147) is represented a transverse section of one of the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jeffrey, Edward C. (Edward Charles), b. 1866. Chicago, Ill. , The University of Chicago Press
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