. Fossil plants : for students of botany and geology . Paleobotany. 330 FI'LICALES [CH. walls and more irregular shape. The protoxyleni, px, is repre- sented by groups of narrower elements rather deeply immersed in the peripheral part of the metaxylem. A many-layered pericycle, per, and traces of an endodermis, en, succeed the phloem, ph., which is characterised by several rows of large contiguous sieve-tubes ; beyond the endodermis is a broad thin- walled inner cortex. The leaf-traces arise as in Zalesskya, but the protoxylem in Thamnopteris is at first central; as the per en l^Jt jiX a. Fig.
. Fossil plants : for students of botany and geology . Paleobotany. 330 FI'LICALES [CH. walls and more irregular shape. The protoxyleni, px, is repre- sented by groups of narrower elements rather deeply immersed in the peripheral part of the metaxylem. A many-layered pericycle, per, and traces of an endodermis, en, succeed the phloem, ph., which is characterised by several rows of large contiguous sieve-tubes ; beyond the endodermis is a broad thin- walled inner cortex. The leaf-traces arise as in Zalesskya, but the protoxylem in Thamnopteris is at first central; as the per en l^Jt jiX a. Fig. 250. Thamnopteris Schlechtendalii (Eioh.). Part of stele : a, outer xylem; b, inner xylem. (After Kidston and Gwynne-Vaughan. x 13.) trace passes outwards a group of parenchyma appears immedi- ately internal to the protoxylem elements and gradually assumes the form of a bay of thin-walled tissue on the inner concave face of the curved xylem. The next stage is the repeated division of the protoxylem strand until, in the sclerotic outer cortex, the traces acquire the Osmundaceous structure (fig. 312, A, p. 453). The petiole bases have stipular wings as in Todea and 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 Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
