. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. 182 THE MARATTIALES The separated xylems become joined lower down into a single transverse plate, just before the junction of the strand with the trace from the third leaf (fig. i66, H), with which it joins in the same way and is continued downward to the junction with the strand arising from the fusion of the second leaf trace with the cotyledon. Above the junction of the first and second leaves, the stele of the second root, which grows vertically downward, joins the stele
. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. 182 THE MARATTIALES The separated xylems become joined lower down into a single transverse plate, just before the junction of the strand with the trace from the third leaf (fig. i66, H), with which it joins in the same way and is continued downward to the junction with the strand arising from the fusion of the second leaf trace with the cotyledon. Above the junction of the first and second leaves, the stele of the second root, which grows vertically downward, joins the stele formed by the junction of the three youngest leaf traces. Above the junction the section of the bundle is nearly circular in outline, the large tracheids forming a broken group in the center of the bundle, quite like a. Fig. i66. A-C. Series of transverse sections from a sporophyte of Kaulfmsia, of about same age as that shown in fig. i6c. D. Stem apex. £> j H-J. Three sections lower down. K. Central vascular cylinder still lower down. corresponding stage in Danaa. Some of the cells adjacent to the bundle show the typical thickenings on the radial walls, indicating that they belong to the endodermis, but the hmits of the endodermis are extremely vague. In this plant two mucilage ducts had developed in the fourth leaf, one on each side of the vascular bundle (fig. 166, B, m). The second root is stouter than the primary one and its bundle is triarch. The mycorrhiza present in the first root could not be detected in the second root, but possibly may be developed at a later stage. All of the roots are provided with root. 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 Campbell, Douglas Houghton, 1859-1953. Washington, D. C. , Carnegie Institution of Washington
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