. Carnegie Institution of Washington publication. A Fig. 131. A. Section of petiole of cotyledon of Danxa elliptica. X75. B. The vascular bundle. X200. C. Section of a peltate scale. X7J. The section of the petiole of the cotyledon in Dancea (fig. 131) is nearly cir- cular, and the wings found in the other forms are almost entirely obliterated. The ground tissue is composed of undifferentiated parenchyma, with no trace of tan- nin cells. The vascular bundle is circular in outline, with a small group of three or four tracheids placed somewhat toward the inner side of the bundle, but sepa- rated
. Carnegie Institution of Washington publication. A Fig. 131. A. Section of petiole of cotyledon of Danxa elliptica. X75. B. The vascular bundle. X200. C. Section of a peltate scale. X7J. The section of the petiole of the cotyledon in Dancea (fig. 131) is nearly cir- cular, and the wings found in the other forms are almost entirely obliterated. The ground tissue is composed of undifferentiated parenchyma, with no trace of tan- nin cells. The vascular bundle is circular in outline, with a small group of three or four tracheids placed somewhat toward the inner side of the bundle, but sepa- rated from the outside by about two rows of cells, probably phloem, but not showing any differentiation. Small protophloem elements, staining darkly, can be seen upon the dorsal side of the bundle and an occasional similar cell can be. Fig. 172. A. Two longitudinal sections of a somewhat older sporophyte of M. dougtasii. B. Apical region of stem, showing apical cell and second leaf. /'. X200. seen toward the ventral side, but most of the ventral surface is destitute of these. The petiole broadens at its base, becoming flattened, and in this region the inner phloem disappears and the bundle becomes collateral, as it is in Ophtoglossum. The tracheary tissue of the cotyledon in all of the Marattiacen* is composed of slender, reticulately marked tracheids, like those of Ophtoglossum. Sieve tubes are prob-. 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 Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
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